<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2025 Workiva-->
<!--r:039bca1c-9e67-4fe8-816e-3802062d957f,g:23d13ac7-c7fb-481b-bc82-4dd585165b9d-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.mongodb.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONS" xlink:type="simple" xlink:href="mdb-20250430.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONS"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_068c1494-5a7d-4a75-a03b-24709cfd2526" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_e4461211-800f-4679-923f-130dfa8fc5a8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_068c1494-5a7d-4a75-a03b-24709cfd2526" xlink:to="loc_us-gaap_StatementTable_e4461211-800f-4679-923f-130dfa8fc5a8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_2f2a5e4f-0ce1-45b8-8ee1-ebf97b5c0049" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_e4461211-800f-4679-923f-130dfa8fc5a8" xlink:to="loc_srt_ProductOrServiceAxis_2f2a5e4f-0ce1-45b8-8ee1-ebf97b5c0049" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_2f2a5e4f-0ce1-45b8-8ee1-ebf97b5c0049_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_2f2a5e4f-0ce1-45b8-8ee1-ebf97b5c0049" xlink:to="loc_srt_ProductsAndServicesDomain_2f2a5e4f-0ce1-45b8-8ee1-ebf97b5c0049_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_9dda1038-4068-4ad5-a791-8be52a8f7fde" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_2f2a5e4f-0ce1-45b8-8ee1-ebf97b5c0049" xlink:to="loc_srt_ProductsAndServicesDomain_9dda1038-4068-4ad5-a791-8be52a8f7fde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicenseMember_6aca172d-2fb7-4c61-8f3d-fa79da5cd5a6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LicenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_9dda1038-4068-4ad5-a791-8be52a8f7fde" xlink:to="loc_us-gaap_LicenseMember_6aca172d-2fb7-4c61-8f3d-fa79da5cd5a6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceMember_f5275117-7c32-4009-aa5e-0774b92a6030" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_9dda1038-4068-4ad5-a791-8be52a8f7fde" xlink:to="loc_us-gaap_ServiceMember_f5275117-7c32-4009-aa5e-0774b92a6030" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_4b1a79a6-a4c9-4755-a50e-33e0df9a176d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_068c1494-5a7d-4a75-a03b-24709cfd2526" xlink:to="loc_us-gaap_RevenuesAbstract_4b1a79a6-a4c9-4755-a50e-33e0df9a176d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_fe70c79d-1fc5-486b-880a-cdd19df83fa3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_4b1a79a6-a4c9-4755-a50e-33e0df9a176d" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_fe70c79d-1fc5-486b-880a-cdd19df83fa3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfRevenueAbstract_637c3614-6998-409b-bbd8-a12441e19e88" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfRevenueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_068c1494-5a7d-4a75-a03b-24709cfd2526" xlink:to="loc_us-gaap_CostOfRevenueAbstract_637c3614-6998-409b-bbd8-a12441e19e88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_5a230cbb-4e61-494e-a4a7-ec0968316b40" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostOfRevenueAbstract_637c3614-6998-409b-bbd8-a12441e19e88" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_5a230cbb-4e61-494e-a4a7-ec0968316b40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_93be88f2-9717-4555-81ed-18ae16f119fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GrossProfit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_068c1494-5a7d-4a75-a03b-24709cfd2526" xlink:to="loc_us-gaap_GrossProfit_93be88f2-9717-4555-81ed-18ae16f119fe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_6636760e-fa14-4691-9336-f009c1101f28" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_068c1494-5a7d-4a75-a03b-24709cfd2526" xlink:to="loc_us-gaap_OperatingExpensesAbstract_6636760e-fa14-4691-9336-f009c1101f28" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpense_658ee1fd-5c39-4ac1-9344-d44534d32e42" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingAndMarketingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_6636760e-fa14-4691-9336-f009c1101f28" xlink:to="loc_us-gaap_SellingAndMarketingExpense_658ee1fd-5c39-4ac1-9344-d44534d32e42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_0412c7fc-16cf-4196-9f2d-53a3e3d85175" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_6636760e-fa14-4691-9336-f009c1101f28" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_0412c7fc-16cf-4196-9f2d-53a3e3d85175" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_722b971b-413c-4c68-88b1-71728bf54e17" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_6636760e-fa14-4691-9336-f009c1101f28" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_722b971b-413c-4c68-88b1-71728bf54e17" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_8b2c32cf-c3c0-42c7-9f0b-7c5eee936d32" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_6636760e-fa14-4691-9336-f009c1101f28" xlink:to="loc_us-gaap_OperatingExpenses_8b2c32cf-c3c0-42c7-9f0b-7c5eee936d32" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_0a3aec7e-46a6-474d-929d-8eb9f269ee3b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_068c1494-5a7d-4a75-a03b-24709cfd2526" xlink:to="loc_us-gaap_OperatingIncomeLoss_0a3aec7e-46a6-474d-929d-8eb9f269ee3b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_6b6082b9-681c-4178-99c8-56bdb3ee126c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherNonoperatingIncomeExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_068c1494-5a7d-4a75-a03b-24709cfd2526" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_6b6082b9-681c-4178-99c8-56bdb3ee126c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeNet_fcedb66b-5f35-436c-8a8f-758cd75c7356" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentIncomeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_6b6082b9-681c-4178-99c8-56bdb3ee126c" xlink:to="loc_us-gaap_InvestmentIncomeNet_fcedb66b-5f35-436c-8a8f-758cd75c7356" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_4a825f50-64b8-46e1-97ff-2e8d7559452c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_6b6082b9-681c-4178-99c8-56bdb3ee126c" xlink:to="loc_us-gaap_InterestExpense_4a825f50-64b8-46e1-97ff-2e8d7559452c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_b4bcda22-9f13-40c7-b82f-4b492a4b7920" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_6b6082b9-681c-4178-99c8-56bdb3ee126c" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_b4bcda22-9f13-40c7-b82f-4b492a4b7920" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_5862c201-e337-4ef9-ae7f-f96b31b5e3b3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_068c1494-5a7d-4a75-a03b-24709cfd2526" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_5862c201-e337-4ef9-ae7f-f96b31b5e3b3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_54cc499f-f1d4-4c7b-9c99-a3c8c087b740" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_068c1494-5a7d-4a75-a03b-24709cfd2526" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_54cc499f-f1d4-4c7b-9c99-a3c8c087b740" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_c83c4894-4c86-4677-bdbe-4d0ddc25b7db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_068c1494-5a7d-4a75-a03b-24709cfd2526" xlink:to="loc_us-gaap_NetIncomeLoss_c83c4894-4c86-4677-bdbe-4d0ddc25b7db" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_8a1b07e3-17cd-4e87-9b08-c4b751b7d572" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_068c1494-5a7d-4a75-a03b-24709cfd2526" xlink:to="loc_us-gaap_EarningsPerShareBasic_8a1b07e3-17cd-4e87-9b08-c4b751b7d572" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_9fabf1d1-c2c2-455b-a4bd-8c1bde594075" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_068c1494-5a7d-4a75-a03b-24709cfd2526" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_9fabf1d1-c2c2-455b-a4bd-8c1bde594075" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="simple" xlink:href="mdb-20250430.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_8d117a8e-44c9-4cf5-a51a-fd61647e5e70" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_0bb2e470-bd18-4bd6-b111-fce587a758f6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_8d117a8e-44c9-4cf5-a51a-fd61647e5e70" xlink:to="loc_us-gaap_StatementTable_0bb2e470-bd18-4bd6-b111-fce587a758f6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_d571a099-c0b0-426b-a18a-571332894f8e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_0bb2e470-bd18-4bd6-b111-fce587a758f6" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_d571a099-c0b0-426b-a18a-571332894f8e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_d571a099-c0b0-426b-a18a-571332894f8e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_d571a099-c0b0-426b-a18a-571332894f8e" xlink:to="loc_us-gaap_EquityComponentDomain_d571a099-c0b0-426b-a18a-571332894f8e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_fc8674a6-0c92-4d3c-951b-19788b559f34" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_d571a099-c0b0-426b-a18a-571332894f8e" xlink:to="loc_us-gaap_EquityComponentDomain_fc8674a6-0c92-4d3c-951b-19788b559f34" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_3ac93adc-c68e-429a-b5a3-9c3a676f3bf5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_fc8674a6-0c92-4d3c-951b-19788b559f34" xlink:to="loc_us-gaap_CommonStockMember_3ac93adc-c68e-429a-b5a3-9c3a676f3bf5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_396aee68-4848-4096-9fe9-f8549b4dae69" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_fc8674a6-0c92-4d3c-951b-19788b559f34" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_396aee68-4848-4096-9fe9-f8549b4dae69" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_47036e77-4cf8-49f3-ad07-56788f8ee32a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_fc8674a6-0c92-4d3c-951b-19788b559f34" xlink:to="loc_us-gaap_TreasuryStockCommonMember_47036e77-4cf8-49f3-ad07-56788f8ee32a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_43035a66-3b0f-407c-9525-cc2d591b3f6b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_fc8674a6-0c92-4d3c-951b-19788b559f34" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_43035a66-3b0f-407c-9525-cc2d591b3f6b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_0f447a2c-ba7f-4084-bcb2-0e64bf3e2f46" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_fc8674a6-0c92-4d3c-951b-19788b559f34" xlink:to="loc_us-gaap_RetainedEarningsMember_0f447a2c-ba7f-4084-bcb2-0e64bf3e2f46" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1d6382e2-4213-434a-a5a2-982e80aa62e1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8d117a8e-44c9-4cf5-a51a-fd61647e5e70" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1d6382e2-4213-434a-a5a2-982e80aa62e1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_b9404cb5-d6d4-4ad3-9773-957847a1ad06" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1d6382e2-4213-434a-a5a2-982e80aa62e1" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_b9404cb5-d6d4-4ad3-9773-957847a1ad06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_c8b48406-315e-4e00-bd44-9f3cc734a6fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1d6382e2-4213-434a-a5a2-982e80aa62e1" xlink:to="loc_us-gaap_StockholdersEquity_c8b48406-315e-4e00-bd44-9f3cc734a6fb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_802ce613-f7ec-41a1-8d9a-36f3d45e2c86" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1d6382e2-4213-434a-a5a2-982e80aa62e1" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_802ce613-f7ec-41a1-8d9a-36f3d45e2c86" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_6c0f8bb4-ed51-4d5e-9b73-7218029139df" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1d6382e2-4213-434a-a5a2-982e80aa62e1" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_6c0f8bb4-ed51-4d5e-9b73-7218029139df" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross_9cf75bfb-11d3-404f-b848-978dbe558678" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1d6382e2-4213-434a-a5a2-982e80aa62e1" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross_9cf75bfb-11d3-404f-b848-978dbe558678" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross_1b4f3e48-cbdb-4fae-80ed-c1017c158ecd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1d6382e2-4213-434a-a5a2-982e80aa62e1" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross_1b4f3e48-cbdb-4fae-80ed-c1017c158ecd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_StockIssuedDuringPeriodSharesPerformanceStockAwardGross_8c4a4d1b-f8e5-4f4e-968a-d83c745cdaaf" xlink:href="mdb-20250430.xsd#mdb_StockIssuedDuringPeriodSharesPerformanceStockAwardGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1d6382e2-4213-434a-a5a2-982e80aa62e1" xlink:to="loc_mdb_StockIssuedDuringPeriodSharesPerformanceStockAwardGross_8c4a4d1b-f8e5-4f4e-968a-d83c745cdaaf" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_StockIssuedDuringPeriodSharesAcquisitionsSubjectToFutureVesting_c64c76ec-5695-4f32-8ded-df22c85ffc70" xlink:href="mdb-20250430.xsd#mdb_StockIssuedDuringPeriodSharesAcquisitionsSubjectToFutureVesting"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1d6382e2-4213-434a-a5a2-982e80aa62e1" xlink:to="loc_mdb_StockIssuedDuringPeriodSharesAcquisitionsSubjectToFutureVesting_c64c76ec-5695-4f32-8ded-df22c85ffc70" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_ad4923e8-2f0d-44b7-aeb8-59441e6ba18b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1d6382e2-4213-434a-a5a2-982e80aa62e1" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_ad4923e8-2f0d-44b7-aeb8-59441e6ba18b" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_d61369d0-8cde-4c78-b3c2-d28fb2625f24" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1d6382e2-4213-434a-a5a2-982e80aa62e1" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_d61369d0-8cde-4c78-b3c2-d28fb2625f24" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_a32eda12-911b-4f70-b373-8a6f78d6d907" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1d6382e2-4213-434a-a5a2-982e80aa62e1" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_a32eda12-911b-4f70-b373-8a6f78d6d907" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax_cd5e90ee-6b7d-46cd-a385-71534974e825" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1d6382e2-4213-434a-a5a2-982e80aa62e1" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax_cd5e90ee-6b7d-46cd-a385-71534974e825" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_6d2eb781-e497-4bd3-a00e-3b876092c8b9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1d6382e2-4213-434a-a5a2-982e80aa62e1" xlink:to="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_6d2eb781-e497-4bd3-a00e-3b876092c8b9" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_AdjustmentToAdditionalPaidInCapitalReclassificationOfDerivatives_dd6fb899-459b-4fe9-8dea-3fb9d5c69772" xlink:href="mdb-20250430.xsd#mdb_AdjustmentToAdditionalPaidInCapitalReclassificationOfDerivatives"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1d6382e2-4213-434a-a5a2-982e80aa62e1" xlink:to="loc_mdb_AdjustmentToAdditionalPaidInCapitalReclassificationOfDerivatives_dd6fb899-459b-4fe9-8dea-3fb9d5c69772" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_a2bedc84-8120-4994-940b-f4f5ff2f8c92" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1d6382e2-4213-434a-a5a2-982e80aa62e1" xlink:to="loc_us-gaap_NetIncomeLoss_a2bedc84-8120-4994-940b-f4f5ff2f8c92" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_ebc3185c-6ac1-4b83-a04b-236e055df667" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_fe3378f1-33fe-4a1e-a1d4-10462112ef50" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/FairValueMeasurementsScheduleofFinancialAssetsandLiabilitiesDetails" xlink:type="simple" xlink:href="mdb-20250430.xsd#FairValueMeasurementsScheduleofFinancialAssetsandLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/FairValueMeasurementsScheduleofFinancialAssetsandLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_c777eb26-df55-4cef-bfa3-a308fa92d357" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_eca4f1b1-7484-48d2-b0bb-7121f20f9b84" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_c777eb26-df55-4cef-bfa3-a308fa92d357" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_eca4f1b1-7484-48d2-b0bb-7121f20f9b84" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_ce3f59cc-70d2-4792-a12e-27899f88b113" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_eca4f1b1-7484-48d2-b0bb-7121f20f9b84" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_ce3f59cc-70d2-4792-a12e-27899f88b113" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_ce3f59cc-70d2-4792-a12e-27899f88b113_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_ce3f59cc-70d2-4792-a12e-27899f88b113" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_ce3f59cc-70d2-4792-a12e-27899f88b113_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_385528a3-85f8-48ed-b803-b53d1fa62474" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_ce3f59cc-70d2-4792-a12e-27899f88b113" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_385528a3-85f8-48ed-b803-b53d1fa62474" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_c28a72ba-e41c-4d66-9c71-bfedad99d980" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_385528a3-85f8-48ed-b803-b53d1fa62474" xlink:to="loc_us-gaap_MoneyMarketFundsMember_c28a72ba-e41c-4d66-9c71-bfedad99d980" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_d142f014-2e29-4efe-b6c9-01421af11505" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_eca4f1b1-7484-48d2-b0bb-7121f20f9b84" xlink:to="loc_us-gaap_FinancialInstrumentAxis_d142f014-2e29-4efe-b6c9-01421af11505" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_d142f014-2e29-4efe-b6c9-01421af11505_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_d142f014-2e29-4efe-b6c9-01421af11505" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_d142f014-2e29-4efe-b6c9-01421af11505_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4543ccf0-58ec-4fbe-9857-1a1eead12b58" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_d142f014-2e29-4efe-b6c9-01421af11505" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4543ccf0-58ec-4fbe-9857-1a1eead12b58" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_050e0cf1-7b58-44df-b4be-e1ae05210f89" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4543ccf0-58ec-4fbe-9857-1a1eead12b58" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_050e0cf1-7b58-44df-b4be-e1ae05210f89" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_99a617c7-cdc4-4c27-b9aa-8bf7c6b34af0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_eca4f1b1-7484-48d2-b0bb-7121f20f9b84" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_99a617c7-cdc4-4c27-b9aa-8bf7c6b34af0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_99a617c7-cdc4-4c27-b9aa-8bf7c6b34af0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_99a617c7-cdc4-4c27-b9aa-8bf7c6b34af0" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_99a617c7-cdc4-4c27-b9aa-8bf7c6b34af0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_161ac1fb-66af-4674-950e-8026bc6a4376" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_99a617c7-cdc4-4c27-b9aa-8bf7c6b34af0" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_161ac1fb-66af-4674-950e-8026bc6a4376" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_9439de0f-e01d-489f-9ee0-0215b6a3112b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_161ac1fb-66af-4674-950e-8026bc6a4376" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_9439de0f-e01d-489f-9ee0-0215b6a3112b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_6e3d29e9-a3ac-4347-b519-415974b594f8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_161ac1fb-66af-4674-950e-8026bc6a4376" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_6e3d29e9-a3ac-4347-b519-415974b594f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_0c39cd31-8766-411d-8a52-10b0df507e0b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_161ac1fb-66af-4674-950e-8026bc6a4376" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_0c39cd31-8766-411d-8a52-10b0df507e0b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_d0f1fe1d-bc39-429e-b3b7-b3fdc602256f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_eca4f1b1-7484-48d2-b0bb-7121f20f9b84" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_d0f1fe1d-bc39-429e-b3b7-b3fdc602256f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_d0f1fe1d-bc39-429e-b3b7-b3fdc602256f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_d0f1fe1d-bc39-429e-b3b7-b3fdc602256f" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_d0f1fe1d-bc39-429e-b3b7-b3fdc602256f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_49520aea-fc1e-48fc-8b96-a3747cd26600" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_d0f1fe1d-bc39-429e-b3b7-b3fdc602256f" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_49520aea-fc1e-48fc-8b96-a3747cd26600" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_4a2810d4-7d1a-4f44-abf5-72316335235e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_49520aea-fc1e-48fc-8b96-a3747cd26600" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_4a2810d4-7d1a-4f44-abf5-72316335235e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_d3052dc4-71cb-4f06-9c5c-91bef8030586" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_c777eb26-df55-4cef-bfa3-a308fa92d357" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_d3052dc4-71cb-4f06-9c5c-91bef8030586" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAbstract_c0dec5f8-5e98-4351-8f44-d5c199488043" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_d3052dc4-71cb-4f06-9c5c-91bef8030586" xlink:to="loc_us-gaap_CashAndCashEquivalentsAbstract_c0dec5f8-5e98-4351-8f44-d5c199488043" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_54c18b3d-910c-43e9-a1c3-cbd7b4a4d159" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsAbstract_c0dec5f8-5e98-4351-8f44-d5c199488043" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_54c18b3d-910c-43e9-a1c3-cbd7b4a4d159" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermInvestmentsAbstract_81511337-6451-4d3f-a61d-148a566a0636" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermInvestmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_d3052dc4-71cb-4f06-9c5c-91bef8030586" xlink:to="loc_us-gaap_ShortTermInvestmentsAbstract_81511337-6451-4d3f-a61d-148a566a0636" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_1074b801-ff8f-45fe-b8de-70c84504d997" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermInvestmentsAbstract_81511337-6451-4d3f-a61d-148a566a0636" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_1074b801-ff8f-45fe-b8de-70c84504d997" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_ee071fae-de1c-4476-96ce-73e6e3312253" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_d3052dc4-71cb-4f06-9c5c-91bef8030586" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_ee071fae-de1c-4476-96ce-73e6e3312253" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/FairValueMeasurementsMarketableSecuritiesDetails" xlink:type="simple" xlink:href="mdb-20250430.xsd#FairValueMeasurementsMarketableSecuritiesDetails"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/FairValueMeasurementsMarketableSecuritiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_58252918-214b-4776-a442-bf5d40060817" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8e020dfc-389b-4a7e-a444-3d91b4f4825c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_58252918-214b-4776-a442-bf5d40060817" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8e020dfc-389b-4a7e-a444-3d91b4f4825c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_6ae20aca-a4de-4ab8-9aee-f0b0bc63ad7d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8e020dfc-389b-4a7e-a444-3d91b4f4825c" xlink:to="loc_us-gaap_FinancialInstrumentAxis_6ae20aca-a4de-4ab8-9aee-f0b0bc63ad7d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_6ae20aca-a4de-4ab8-9aee-f0b0bc63ad7d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_6ae20aca-a4de-4ab8-9aee-f0b0bc63ad7d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_6ae20aca-a4de-4ab8-9aee-f0b0bc63ad7d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_18fa790f-e14e-4918-90be-62474113cfa2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_6ae20aca-a4de-4ab8-9aee-f0b0bc63ad7d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_18fa790f-e14e-4918-90be-62474113cfa2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_d7e8850e-f2ff-4763-86ff-e53093e73002" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_18fa790f-e14e-4918-90be-62474113cfa2" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_d7e8850e-f2ff-4763-86ff-e53093e73002" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostCurrent_fdbd11ef-b50b-4ab7-bebd-ede7e807a7ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_58252918-214b-4776-a442-bf5d40060817" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostCurrent_fdbd11ef-b50b-4ab7-bebd-ede7e807a7ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostNoncurrent_6b60b907-7fcf-4777-ad33-e9c25fda1c26" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_58252918-214b-4776-a442-bf5d40060817" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostNoncurrent_6b60b907-7fcf-4777-ad33-e9c25fda1c26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_8377a56c-8c20-497a-8237-b84121c9b237" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_58252918-214b-4776-a442-bf5d40060817" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_8377a56c-8c20-497a-8237-b84121c9b237" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_DebtSecuritiesAvailableForSaleUnrealizedGainLossCurrent_68fe30a2-a018-47aa-8161-57cf966e5d08" xlink:href="mdb-20250430.xsd#mdb_DebtSecuritiesAvailableForSaleUnrealizedGainLossCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_58252918-214b-4776-a442-bf5d40060817" xlink:to="loc_mdb_DebtSecuritiesAvailableForSaleUnrealizedGainLossCurrent_68fe30a2-a018-47aa-8161-57cf966e5d08" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_DebtSecuritiesAvailableForSaleUnrealizedGainLossNoncurrent_17409922-ded3-4b92-87d2-b8ce463104f8" xlink:href="mdb-20250430.xsd#mdb_DebtSecuritiesAvailableForSaleUnrealizedGainLossNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_58252918-214b-4776-a442-bf5d40060817" xlink:to="loc_mdb_DebtSecuritiesAvailableForSaleUnrealizedGainLossNoncurrent_17409922-ded3-4b92-87d2-b8ce463104f8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedGainLoss_2a1a3f89-a584-435f-9e10-f386d72e42bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_58252918-214b-4776-a442-bf5d40060817" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedGainLoss_2a1a3f89-a584-435f-9e10-f386d72e42bf" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesCurrent_77d58d91-debf-4f95-b83b-8d454c15ba9f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketableSecuritiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_58252918-214b-4776-a442-bf5d40060817" xlink:to="loc_us-gaap_MarketableSecuritiesCurrent_77d58d91-debf-4f95-b83b-8d454c15ba9f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesNoncurrent_b0d68665-3827-43ff-ab1a-9991b4b93348" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketableSecuritiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_58252918-214b-4776-a442-bf5d40060817" xlink:to="loc_us-gaap_MarketableSecuritiesNoncurrent_b0d68665-3827-43ff-ab1a-9991b4b93348" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecurities_eb54003f-20db-4d17-97a2-ee677e9b6d29" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketableSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_58252918-214b-4776-a442-bf5d40060817" xlink:to="loc_us-gaap_MarketableSecurities_eb54003f-20db-4d17-97a2-ee677e9b6d29" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/FairValueMeasurementsNarrativeDetails" xlink:type="simple" xlink:href="mdb-20250430.xsd#FairValueMeasurementsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/FairValueMeasurementsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_e6293218-0146-4535-a3f0-a5eb33c9aeb4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_f813a188-6504-4913-a641-0d386fd9ba30" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_e6293218-0146-4535-a3f0-a5eb33c9aeb4" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_f813a188-6504-4913-a641-0d386fd9ba30" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_51c0e4aa-39ce-41fa-bdc6-45f2fffb2613" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_f813a188-6504-4913-a641-0d386fd9ba30" xlink:to="loc_us-gaap_FinancialInstrumentAxis_51c0e4aa-39ce-41fa-bdc6-45f2fffb2613" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_51c0e4aa-39ce-41fa-bdc6-45f2fffb2613_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_51c0e4aa-39ce-41fa-bdc6-45f2fffb2613" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_51c0e4aa-39ce-41fa-bdc6-45f2fffb2613_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9ede926e-f2ec-4ada-9cc6-3b62e0ede0a0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_51c0e4aa-39ce-41fa-bdc6-45f2fffb2613" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9ede926e-f2ec-4ada-9cc6-3b62e0ede0a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_9c8bee51-46ea-4bea-942f-a717edae62b8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9ede926e-f2ec-4ada-9cc6-3b62e0ede0a0" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_9c8bee51-46ea-4bea-942f-a717edae62b8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecurityOwnedNotReadilyMarketableAxis_5cf2fa1b-d7bb-4981-bbed-61aebcef3b8d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SecurityOwnedNotReadilyMarketableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_f813a188-6504-4913-a641-0d386fd9ba30" xlink:to="loc_us-gaap_SecurityOwnedNotReadilyMarketableAxis_5cf2fa1b-d7bb-4981-bbed-61aebcef3b8d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecurityOwnedNotReadilyMarketableNameDomain_5cf2fa1b-d7bb-4981-bbed-61aebcef3b8d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SecurityOwnedNotReadilyMarketableNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SecurityOwnedNotReadilyMarketableAxis_5cf2fa1b-d7bb-4981-bbed-61aebcef3b8d" xlink:to="loc_us-gaap_SecurityOwnedNotReadilyMarketableNameDomain_5cf2fa1b-d7bb-4981-bbed-61aebcef3b8d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecurityOwnedNotReadilyMarketableNameDomain_3c1e5dcf-3a06-4171-bda7-981e33ad6d17" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SecurityOwnedNotReadilyMarketableNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SecurityOwnedNotReadilyMarketableAxis_5cf2fa1b-d7bb-4981-bbed-61aebcef3b8d" xlink:to="loc_us-gaap_SecurityOwnedNotReadilyMarketableNameDomain_3c1e5dcf-3a06-4171-bda7-981e33ad6d17" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_NonMarketableSecuritiesMember_65272127-b8e7-4405-ac4e-d9cd843e0c08" xlink:href="mdb-20250430.xsd#mdb_NonMarketableSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SecurityOwnedNotReadilyMarketableNameDomain_3c1e5dcf-3a06-4171-bda7-981e33ad6d17" xlink:to="loc_mdb_NonMarketableSecuritiesMember_65272127-b8e7-4405-ac4e-d9cd843e0c08" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedGainLoss_52f04e10-efd4-4cdb-83a0-85dd4bcc124e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_e6293218-0146-4535-a3f0-a5eb33c9aeb4" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedGainLoss_52f04e10-efd4-4cdb-83a0-85dd4bcc124e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount_27153952-4466-4e23-afc0-11210d2fab92" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_e6293218-0146-4535-a3f0-a5eb33c9aeb4" xlink:to="loc_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount_27153952-4466-4e23-afc0-11210d2fab92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireInvestments_ef7af716-01a3-4320-8b73-4e51f72f1fd5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_e6293218-0146-4535-a3f0-a5eb33c9aeb4" xlink:to="loc_us-gaap_PaymentsToAcquireInvestments_ef7af716-01a3-4320-8b73-4e51f72f1fd5" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/GoodwillandAcquiredIntangibleAssetsNetAdditionalInformationDetails" xlink:type="simple" xlink:href="mdb-20250430.xsd#GoodwillandAcquiredIntangibleAssetsNetAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/GoodwillandAcquiredIntangibleAssetsNetAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_9a831be0-287c-4225-bfe3-c928bbca1ec1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_6526e78e-1c8b-4bfb-9e21-d5762e28b6d2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_9a831be0-287c-4225-bfe3-c928bbca1ec1" xlink:to="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_6526e78e-1c8b-4bfb-9e21-d5762e28b6d2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_6ef50336-4c44-4b30-b075-75aac16d24c4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_6526e78e-1c8b-4bfb-9e21-d5762e28b6d2" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_6ef50336-4c44-4b30-b075-75aac16d24c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_6ef50336-4c44-4b30-b075-75aac16d24c4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_6ef50336-4c44-4b30-b075-75aac16d24c4" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_6ef50336-4c44-4b30-b075-75aac16d24c4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_41477067-9e01-4cb7-9dfc-7ff03bfb3517" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_6ef50336-4c44-4b30-b075-75aac16d24c4" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_41477067-9e01-4cb7-9dfc-7ff03bfb3517" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternetDomainNamesMember_4fb49996-b3a6-4926-b4f0-633bcc16938a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InternetDomainNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_41477067-9e01-4cb7-9dfc-7ff03bfb3517" xlink:to="loc_us-gaap_InternetDomainNamesMember_4fb49996-b3a6-4926-b4f0-633bcc16938a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsAxis_8d964a4c-f90b-4792-8c51-1e501fcd7d47" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_6526e78e-1c8b-4bfb-9e21-d5762e28b6d2" xlink:to="loc_us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsAxis_8d964a4c-f90b-4792-8c51-1e501fcd7d47" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsDomain_8d964a4c-f90b-4792-8c51-1e501fcd7d47_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsAxis_8d964a4c-f90b-4792-8c51-1e501fcd7d47" xlink:to="loc_us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsDomain_8d964a4c-f90b-4792-8c51-1e501fcd7d47_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsDomain_7c74e03e-32a6-4936-bfa9-862befca8987" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsAxis_8d964a4c-f90b-4792-8c51-1e501fcd7d47" xlink:to="loc_us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsDomain_7c74e03e-32a6-4936-bfa9-862befca8987" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_4405ed97-b905-4c41-bfb4-e251d431c116" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_6526e78e-1c8b-4bfb-9e21-d5762e28b6d2" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_4405ed97-b905-4c41-bfb4-e251d431c116" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4405ed97-b905-4c41-bfb4-e251d431c116_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_4405ed97-b905-4c41-bfb4-e251d431c116" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4405ed97-b905-4c41-bfb4-e251d431c116_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fa919557-85e2-4560-ae02-af8f67742462" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_4405ed97-b905-4c41-bfb4-e251d431c116" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fa919557-85e2-4560-ae02-af8f67742462" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_IPAddressesMember_c7e33c22-d144-4373-9081-061d85ebfeb8" xlink:href="mdb-20250430.xsd#mdb_IPAddressesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fa919557-85e2-4560-ae02-af8f67742462" xlink:to="loc_mdb_IPAddressesMember_c7e33c22-d144-4373-9081-061d85ebfeb8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_485ca17f-2082-4777-9e58-4d2eb1208ae4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_9a831be0-287c-4225-bfe3-c928bbca1ec1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_485ca17f-2082-4777-9e58-4d2eb1208ae4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_a6150d35-2d15-4d1c-8a62-4994de16669c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_9a831be0-287c-4225-bfe3-c928bbca1ec1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_a6150d35-2d15-4d1c-8a62-4994de16669c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_b134629f-6b2e-4e5d-a833-9e385c14e7b1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_9a831be0-287c-4225-bfe3-c928bbca1ec1" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_b134629f-6b2e-4e5d-a833-9e385c14e7b1" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/GoodwillandAcquiredIntangibleAssetsNetScheduleofIntangibleAssetsDetails" xlink:type="simple" xlink:href="mdb-20250430.xsd#GoodwillandAcquiredIntangibleAssetsNetScheduleofIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/GoodwillandAcquiredIntangibleAssetsNetScheduleofIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_152b04df-fe98-4688-b3d8-83d2637c133a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_9cae62e2-914b-46e5-befd-ecbc366aef43" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_152b04df-fe98-4688-b3d8-83d2637c133a" xlink:to="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_9cae62e2-914b-46e5-befd-ecbc366aef43" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e4d26bfd-3f18-4db3-821e-0ec5bd2a5a1a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_9cae62e2-914b-46e5-befd-ecbc366aef43" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e4d26bfd-3f18-4db3-821e-0ec5bd2a5a1a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e4d26bfd-3f18-4db3-821e-0ec5bd2a5a1a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e4d26bfd-3f18-4db3-821e-0ec5bd2a5a1a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e4d26bfd-3f18-4db3-821e-0ec5bd2a5a1a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c8dcb16b-a9f4-4ea4-96de-8290d5d32eb5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e4d26bfd-3f18-4db3-821e-0ec5bd2a5a1a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c8dcb16b-a9f4-4ea4-96de-8290d5d32eb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_b3a33b60-6668-40bc-ad8a-e8dd6573cb81" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DevelopedTechnologyRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c8dcb16b-a9f4-4ea4-96de-8290d5d32eb5" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_b3a33b60-6668-40bc-ad8a-e8dd6573cb81" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_40cd384e-d41a-49d4-bda7-7aa01be6b9d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c8dcb16b-a9f4-4ea4-96de-8290d5d32eb5" xlink:to="loc_us-gaap_CustomerRelationshipsMember_40cd384e-d41a-49d4-bda7-7aa01be6b9d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternetDomainNamesMember_7f14ac45-1705-4f5c-816a-54bae04d726e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InternetDomainNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c8dcb16b-a9f4-4ea4-96de-8290d5d32eb5" xlink:to="loc_us-gaap_InternetDomainNamesMember_7f14ac45-1705-4f5c-816a-54bae04d726e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_4c3fab65-fe97-47c9-9941-3bea3f93241c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_152b04df-fe98-4688-b3d8-83d2637c133a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_4c3fab65-fe97-47c9-9941-3bea3f93241c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_c61af5c1-c924-4262-ab71-15529c53af2f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_152b04df-fe98-4688-b3d8-83d2637c133a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_c61af5c1-c924-4262-ab71-15529c53af2f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_99ea57cb-7d42-4930-a90b-ab4f182f35bd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_152b04df-fe98-4688-b3d8-83d2637c133a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_99ea57cb-7d42-4930-a90b-ab4f182f35bd" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/BusinessCombinationsAdditionalInformationDetails" xlink:type="simple" xlink:href="mdb-20250430.xsd#BusinessCombinationsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/BusinessCombinationsAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_f0b4f341-bcee-4b01-95cf-8ccb76da2a15" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_0fe2535c-9092-4689-a43e-685202e24fc9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f0b4f341-bcee-4b01-95cf-8ccb76da2a15" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_0fe2535c-9092-4689-a43e-685202e24fc9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_d95ed7a8-f5ab-41e0-8581-eb97cbf149d8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_0fe2535c-9092-4689-a43e-685202e24fc9" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_d95ed7a8-f5ab-41e0-8581-eb97cbf149d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d95ed7a8-f5ab-41e0-8581-eb97cbf149d8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_d95ed7a8-f5ab-41e0-8581-eb97cbf149d8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d95ed7a8-f5ab-41e0-8581-eb97cbf149d8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d917be95-4cef-4f47-aa9c-1b9f221e2010" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_d95ed7a8-f5ab-41e0-8581-eb97cbf149d8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d917be95-4cef-4f47-aa9c-1b9f221e2010" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_VoyageAIInnovationsInc.Member_7ac9f6f7-d08b-409f-8b59-2db33a5f5fef" xlink:href="mdb-20250430.xsd#mdb_VoyageAIInnovationsInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d917be95-4cef-4f47-aa9c-1b9f221e2010" xlink:to="loc_mdb_VoyageAIInnovationsInc.Member_7ac9f6f7-d08b-409f-8b59-2db33a5f5fef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_GrainiteIncMember_3916d198-9a6f-4d5f-8fb1-1f0a48e4cb2a" xlink:href="mdb-20250430.xsd#mdb_GrainiteIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d917be95-4cef-4f47-aa9c-1b9f221e2010" xlink:to="loc_mdb_GrainiteIncMember_3916d198-9a6f-4d5f-8fb1-1f0a48e4cb2a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_648a1062-a9b8-455a-b0c4-51df080edc13" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_0fe2535c-9092-4689-a43e-685202e24fc9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_648a1062-a9b8-455a-b0c4-51df080edc13" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_648a1062-a9b8-455a-b0c4-51df080edc13_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_648a1062-a9b8-455a-b0c4-51df080edc13" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_648a1062-a9b8-455a-b0c4-51df080edc13_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_7a66aaf0-c49d-4905-b1e5-12732af16249" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_648a1062-a9b8-455a-b0c4-51df080edc13" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_7a66aaf0-c49d-4905-b1e5-12732af16249" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember_7b4c6d77-42a5-4ed0-91cf-d68b54eda174" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DevelopedTechnologyRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_7a66aaf0-c49d-4905-b1e5-12732af16249" xlink:to="loc_us-gaap_DevelopedTechnologyRightsMember_7b4c6d77-42a5-4ed0-91cf-d68b54eda174" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_cd095bad-4228-4195-9cf6-5dbddd4df47e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_0fe2535c-9092-4689-a43e-685202e24fc9" xlink:to="loc_us-gaap_AwardTypeAxis_cd095bad-4228-4195-9cf6-5dbddd4df47e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cd095bad-4228-4195-9cf6-5dbddd4df47e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_cd095bad-4228-4195-9cf6-5dbddd4df47e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cd095bad-4228-4195-9cf6-5dbddd4df47e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_eb44f78e-7eba-468f-905d-d10de6765624" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_cd095bad-4228-4195-9cf6-5dbddd4df47e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_eb44f78e-7eba-468f-905d-d10de6765624" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_6267f55c-1024-4829-8ae4-659c6d76c6ad" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_eb44f78e-7eba-468f-905d-d10de6765624" xlink:to="loc_us-gaap_RestrictedStockMember_6267f55c-1024-4829-8ae4-659c6d76c6ad" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_cc90a684-2cb3-4ee1-89d2-009431f79cfd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_eb44f78e-7eba-468f-905d-d10de6765624" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_cc90a684-2cb3-4ee1-89d2-009431f79cfd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_StockIssuedDuringPeriodSharesAcquisitionsSubjectToFutureVesting_bf1dc9bf-f927-48a8-b0bd-14c05c3daed0" xlink:href="mdb-20250430.xsd#mdb_StockIssuedDuringPeriodSharesAcquisitionsSubjectToFutureVesting"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f0b4f341-bcee-4b01-95cf-8ccb76da2a15" xlink:to="loc_mdb_StockIssuedDuringPeriodSharesAcquisitionsSubjectToFutureVesting_bf1dc9bf-f927-48a8-b0bd-14c05c3daed0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_05717941-9e51-44a4-b051-4191bc4d75aa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f0b4f341-bcee-4b01-95cf-8ccb76da2a15" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_05717941-9e51-44a4-b051-4191bc4d75aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_StockIssuedDuringPeriodValueAcquisitionsSubjectToFutureVesting_289ffc09-4813-4e3b-a0fb-5c4443612a2f" xlink:href="mdb-20250430.xsd#mdb_StockIssuedDuringPeriodValueAcquisitionsSubjectToFutureVesting"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f0b4f341-bcee-4b01-95cf-8ccb76da2a15" xlink:to="loc_mdb_StockIssuedDuringPeriodValueAcquisitionsSubjectToFutureVesting_289ffc09-4813-4e3b-a0fb-5c4443612a2f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_67e1896f-c552-4c3a-9b16-15b1b84ae850" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f0b4f341-bcee-4b01-95cf-8ccb76da2a15" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_67e1896f-c552-4c3a-9b16-15b1b84ae850" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_3954a411-6bfb-464d-a1a6-e2ee99e23e8e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f0b4f341-bcee-4b01-95cf-8ccb76da2a15" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_3954a411-6bfb-464d-a1a6-e2ee99e23e8e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_fcb37204-b1d7-41f4-8486-a653bdc14e0f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f0b4f341-bcee-4b01-95cf-8ccb76da2a15" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_fcb37204-b1d7-41f4-8486-a653bdc14e0f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_571dcc74-505f-4b86-babc-11e27f8d6520" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f0b4f341-bcee-4b01-95cf-8ccb76da2a15" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_571dcc74-505f-4b86-babc-11e27f8d6520" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_3e06c7c9-463d-4fcf-9feb-29a69e5803ac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f0b4f341-bcee-4b01-95cf-8ccb76da2a15" xlink:to="loc_us-gaap_Goodwill_3e06c7c9-463d-4fcf-9feb-29a69e5803ac" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/BusinessCombinationsPurchasePriceConsiderationDetails" xlink:type="simple" xlink:href="mdb-20250430.xsd#BusinessCombinationsPurchasePriceConsiderationDetails"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/BusinessCombinationsPurchasePriceConsiderationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_79a38486-d888-46a1-a64f-a8c890c8dad5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_249617a1-a099-4294-980a-a0d325de922a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_79a38486-d888-46a1-a64f-a8c890c8dad5" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_249617a1-a099-4294-980a-a0d325de922a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_fa155975-8aea-4dda-9b35-e90a643deaeb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_249617a1-a099-4294-980a-a0d325de922a" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_fa155975-8aea-4dda-9b35-e90a643deaeb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fa155975-8aea-4dda-9b35-e90a643deaeb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_fa155975-8aea-4dda-9b35-e90a643deaeb" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fa155975-8aea-4dda-9b35-e90a643deaeb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e8d10e55-d87c-4569-9293-2707104ec20f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_fa155975-8aea-4dda-9b35-e90a643deaeb" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e8d10e55-d87c-4569-9293-2707104ec20f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_VoyageAIInnovationsInc.Member_5f70050a-2784-4582-87cb-cf1bedf4c493" xlink:href="mdb-20250430.xsd#mdb_VoyageAIInnovationsInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e8d10e55-d87c-4569-9293-2707104ec20f" xlink:to="loc_mdb_VoyageAIInnovationsInc.Member_5f70050a-2784-4582-87cb-cf1bedf4c493" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityInterestIssuedOrIssuableByTypeAxis_9489998f-bc85-4596-8d7f-10fa4fc34e92" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityInterestIssuedOrIssuableByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_249617a1-a099-4294-980a-a0d325de922a" xlink:to="loc_us-gaap_EquityInterestIssuedOrIssuableByTypeAxis_9489998f-bc85-4596-8d7f-10fa4fc34e92" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityInterestIssuedOrIssuableTypeDomain_9489998f-bc85-4596-8d7f-10fa4fc34e92_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityInterestIssuedOrIssuableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EquityInterestIssuedOrIssuableByTypeAxis_9489998f-bc85-4596-8d7f-10fa4fc34e92" xlink:to="loc_us-gaap_EquityInterestIssuedOrIssuableTypeDomain_9489998f-bc85-4596-8d7f-10fa4fc34e92_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityInterestIssuedOrIssuableTypeDomain_4c21c1d9-818b-4f84-94c4-fb7685116c4e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityInterestIssuedOrIssuableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EquityInterestIssuedOrIssuableByTypeAxis_9489998f-bc85-4596-8d7f-10fa4fc34e92" xlink:to="loc_us-gaap_EquityInterestIssuedOrIssuableTypeDomain_4c21c1d9-818b-4f84-94c4-fb7685116c4e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_0f51192f-97c1-4397-93c5-070e6d0e7999" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityInterestIssuedOrIssuableTypeDomain_4c21c1d9-818b-4f84-94c4-fb7685116c4e" xlink:to="loc_us-gaap_CommonStockMember_0f51192f-97c1-4397-93c5-070e6d0e7999" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_2ef1148f-65d0-4531-a45d-6953feb6fc33" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_79a38486-d888-46a1-a64f-a8c890c8dad5" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_2ef1148f-65d0-4531-a45d-6953feb6fc33" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_9acf9ba6-7188-4dec-a2e9-4064ac7f97c1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_79a38486-d888-46a1-a64f-a8c890c8dad5" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_9acf9ba6-7188-4dec-a2e9-4064ac7f97c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_2d8955e9-898d-4453-b5e7-6be46dfa752a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_79a38486-d888-46a1-a64f-a8c890c8dad5" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_2d8955e9-898d-4453-b5e7-6be46dfa752a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_BusinessAcquisitionNumberOfCommonStockSharesAcquired_a00af45c-4099-4684-9091-3934546cfa26" xlink:href="mdb-20250430.xsd#mdb_BusinessAcquisitionNumberOfCommonStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_79a38486-d888-46a1-a64f-a8c890c8dad5" xlink:to="loc_mdb_BusinessAcquisitionNumberOfCommonStockSharesAcquired_a00af45c-4099-4684-9091-3934546cfa26" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionSharePrice_7114508c-5eb1-42f3-9bdb-1d124a337527" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionSharePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_79a38486-d888-46a1-a64f-a8c890c8dad5" xlink:to="loc_us-gaap_BusinessAcquisitionSharePrice_7114508c-5eb1-42f3-9bdb-1d124a337527" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/BusinessCombinationsAssetsandLiabilitiesAssumedinBusinessAcquisitionDetails" xlink:type="simple" xlink:href="mdb-20250430.xsd#BusinessCombinationsAssetsandLiabilitiesAssumedinBusinessAcquisitionDetails"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/BusinessCombinationsAssetsandLiabilitiesAssumedinBusinessAcquisitionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_495ea34e-5b11-4b68-b37a-a97372a5c226" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8668c80b-f998-469c-9a8d-5c917b32b831" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_495ea34e-5b11-4b68-b37a-a97372a5c226" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8668c80b-f998-469c-9a8d-5c917b32b831" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_dd490f51-3374-4aae-aa85-5e50b189f89c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8668c80b-f998-469c-9a8d-5c917b32b831" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_dd490f51-3374-4aae-aa85-5e50b189f89c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_dd490f51-3374-4aae-aa85-5e50b189f89c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_dd490f51-3374-4aae-aa85-5e50b189f89c" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_dd490f51-3374-4aae-aa85-5e50b189f89c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d81afd9d-077f-4128-9c4b-9e0fe68f8568" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_dd490f51-3374-4aae-aa85-5e50b189f89c" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d81afd9d-077f-4128-9c4b-9e0fe68f8568" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_VoyageAIInnovationsInc.Member_e73a1228-5b94-40cb-9b6d-8cefdd3d64e3" xlink:href="mdb-20250430.xsd#mdb_VoyageAIInnovationsInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d81afd9d-077f-4128-9c4b-9e0fe68f8568" xlink:to="loc_mdb_VoyageAIInnovationsInc.Member_e73a1228-5b94-40cb-9b6d-8cefdd3d64e3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_ea1081b8-a7a5-49dc-8d8e-436f164a9c86" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_495ea34e-5b11-4b68-b37a-a97372a5c226" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_ea1081b8-a7a5-49dc-8d8e-436f164a9c86" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_48f8bb19-20ca-4c83-a930-1b0597578b6c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_ea1081b8-a7a5-49dc-8d8e-436f164a9c86" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_48f8bb19-20ca-4c83-a930-1b0597578b6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets_b5e595c3-196d-4263-9626-29c9b91ee701" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_ea1081b8-a7a5-49dc-8d8e-436f164a9c86" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets_b5e595c3-196d-4263-9626-29c9b91ee701" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_69b4f350-3852-47cc-a345-7d2d3b677875" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_ea1081b8-a7a5-49dc-8d8e-436f164a9c86" xlink:to="loc_us-gaap_Goodwill_69b4f350-3852-47cc-a345-7d2d3b677875" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_1c38c586-b6e7-4395-bc84-7704e23506bc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_ea1081b8-a7a5-49dc-8d8e-436f164a9c86" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_1c38c586-b6e7-4395-bc84-7704e23506bc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_BusinessCombinationRecognizedLiabilityAssumedAccountsPayableAndAccruedExpenses_b4c51eca-1bbe-4593-b777-454b94d9731f" xlink:href="mdb-20250430.xsd#mdb_BusinessCombinationRecognizedLiabilityAssumedAccountsPayableAndAccruedExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_ea1081b8-a7a5-49dc-8d8e-436f164a9c86" xlink:to="loc_mdb_BusinessCombinationRecognizedLiabilityAssumedAccountsPayableAndAccruedExpenses_b4c51eca-1bbe-4593-b777-454b94d9731f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_4ba24b52-321a-4a42-93ea-964ef30544f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_ea1081b8-a7a5-49dc-8d8e-436f164a9c86" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_4ba24b52-321a-4a42-93ea-964ef30544f7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_44f578a5-6934-4dec-993b-e8b79e93a782" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_ea1081b8-a7a5-49dc-8d8e-436f164a9c86" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_44f578a5-6934-4dec-993b-e8b79e93a782" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_34ac4edd-596b-415b-a504-ac34c5b93ae3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_495ea34e-5b11-4b68-b37a-a97372a5c226" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_34ac4edd-596b-415b-a504-ac34c5b93ae3" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/ConvertibleSeniorNotesAdditionalInformationDetails" xlink:type="simple" xlink:href="mdb-20250430.xsd#ConvertibleSeniorNotesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/ConvertibleSeniorNotesAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_4d54cb43-373a-45bf-9f49-769a1fdb0568" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:to="loc_us-gaap_DebtInstrumentTable_4d54cb43-373a-45bf-9f49-769a1fdb0568" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_f0682604-402c-428c-986d-4606d56e1354" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4d54cb43-373a-45bf-9f49-769a1fdb0568" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_f0682604-402c-428c-986d-4606d56e1354" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_f0682604-402c-428c-986d-4606d56e1354_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_f0682604-402c-428c-986d-4606d56e1354" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_f0682604-402c-428c-986d-4606d56e1354_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_75fe0e2c-183b-4b23-944c-4d7622f99e91" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_f0682604-402c-428c-986d-4606d56e1354" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_75fe0e2c-183b-4b23-944c-4d7622f99e91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_01595f61-aa70-43ed-ada1-822dab18ae83" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_75fe0e2c-183b-4b23-944c-4d7622f99e91" xlink:to="loc_us-gaap_ConvertibleDebtMember_01595f61-aa70-43ed-ada1-822dab18ae83" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_fb38fdcd-c59d-478a-8cce-f533578797d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4d54cb43-373a-45bf-9f49-769a1fdb0568" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_fb38fdcd-c59d-478a-8cce-f533578797d1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_fb38fdcd-c59d-478a-8cce-f533578797d1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_fb38fdcd-c59d-478a-8cce-f533578797d1" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_fb38fdcd-c59d-478a-8cce-f533578797d1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_6aec5c5c-118f-44a5-a205-937ed8354866" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_fb38fdcd-c59d-478a-8cce-f533578797d1" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_6aec5c5c-118f-44a5-a205-937ed8354866" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_78de15d7-61e9-49b1-8c8c-98fdb0f155fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_6aec5c5c-118f-44a5-a205-937ed8354866" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_78de15d7-61e9-49b1-8c8c-98fdb0f155fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_5f818466-d6e4-404a-b006-eb7a2526e575" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4d54cb43-373a-45bf-9f49-769a1fdb0568" xlink:to="loc_us-gaap_DebtInstrumentAxis_5f818466-d6e4-404a-b006-eb7a2526e575" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5f818466-d6e4-404a-b006-eb7a2526e575_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_5f818466-d6e4-404a-b006-eb7a2526e575" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5f818466-d6e4-404a-b006-eb7a2526e575_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_b145fe97-3da4-4766-a0ab-273bd65a27fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_5f818466-d6e4-404a-b006-eb7a2526e575" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_b145fe97-3da4-4766-a0ab-273bd65a27fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_ConvertibleNotesDue2026Member_4441b1c9-c11b-4f24-81f4-0eec07c0294a" xlink:href="mdb-20250430.xsd#mdb_ConvertibleNotesDue2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b145fe97-3da4-4766-a0ab-273bd65a27fe" xlink:to="loc_mdb_ConvertibleNotesDue2026Member_4441b1c9-c11b-4f24-81f4-0eec07c0294a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_AdditionalConvertibleSeniorNotesDue2026Member_f589feb7-bf1c-45dc-a923-8ffe07e8d86c" xlink:href="mdb-20250430.xsd#mdb_AdditionalConvertibleSeniorNotesDue2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b145fe97-3da4-4766-a0ab-273bd65a27fe" xlink:to="loc_mdb_AdditionalConvertibleSeniorNotesDue2026Member_f589feb7-bf1c-45dc-a923-8ffe07e8d86c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_ConvertibleNotesDue2024Member_6f1356c8-00bb-4cc5-af79-3eac446915ce" xlink:href="mdb-20250430.xsd#mdb_ConvertibleNotesDue2024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b145fe97-3da4-4766-a0ab-273bd65a27fe" xlink:to="loc_mdb_ConvertibleNotesDue2024Member_6f1356c8-00bb-4cc5-af79-3eac446915ce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_e43e1a4a-cc07-4787-afdc-48226bc21372" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4d54cb43-373a-45bf-9f49-769a1fdb0568" xlink:to="loc_srt_RangeAxis_e43e1a4a-cc07-4787-afdc-48226bc21372" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_e43e1a4a-cc07-4787-afdc-48226bc21372_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_e43e1a4a-cc07-4787-afdc-48226bc21372" xlink:to="loc_srt_RangeMember_e43e1a4a-cc07-4787-afdc-48226bc21372_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_98f12517-b3d6-4e6d-b026-54e7aa9dfcba" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_e43e1a4a-cc07-4787-afdc-48226bc21372" xlink:to="loc_srt_RangeMember_98f12517-b3d6-4e6d-b026-54e7aa9dfcba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_f3cbc75a-dad4-4280-9719-7fe7bf70c094" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_98f12517-b3d6-4e6d-b026-54e7aa9dfcba" xlink:to="loc_srt_MinimumMember_f3cbc75a-dad4-4280-9719-7fe7bf70c094" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_a6bb4db0-3bbc-49b9-9329-90e89b031cf4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4d54cb43-373a-45bf-9f49-769a1fdb0568" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_a6bb4db0-3bbc-49b9-9329-90e89b031cf4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_a6bb4db0-3bbc-49b9-9329-90e89b031cf4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_a6bb4db0-3bbc-49b9-9329-90e89b031cf4" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_a6bb4db0-3bbc-49b9-9329-90e89b031cf4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_d299ed39-7272-4c9e-a770-8eb201628bc5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_a6bb4db0-3bbc-49b9-9329-90e89b031cf4" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_d299ed39-7272-4c9e-a770-8eb201628bc5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_cbdb6900-c0c9-40de-9967-feec48c5b617" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_d299ed39-7272-4c9e-a770-8eb201628bc5" xlink:to="loc_us-gaap_ConvertibleDebtMember_cbdb6900-c0c9-40de-9967-feec48c5b617" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtConversionByUniqueDescriptionAxis_626519f1-b2a3-4657-b82e-7864bea862f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtConversionByUniqueDescriptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4d54cb43-373a-45bf-9f49-769a1fdb0568" xlink:to="loc_us-gaap_DebtConversionByUniqueDescriptionAxis_626519f1-b2a3-4657-b82e-7864bea862f4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtConversionNameDomain_626519f1-b2a3-4657-b82e-7864bea862f4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtConversionNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtConversionByUniqueDescriptionAxis_626519f1-b2a3-4657-b82e-7864bea862f4" xlink:to="loc_us-gaap_DebtConversionNameDomain_626519f1-b2a3-4657-b82e-7864bea862f4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtConversionNameDomain_885702c2-1464-4e44-a39d-778c31778738" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtConversionNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtConversionByUniqueDescriptionAxis_626519f1-b2a3-4657-b82e-7864bea862f4" xlink:to="loc_us-gaap_DebtConversionNameDomain_885702c2-1464-4e44-a39d-778c31778738" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashSettlementMember_faaed9cd-3d2b-4877-9a14-c667a452c667" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashSettlementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtConversionNameDomain_885702c2-1464-4e44-a39d-778c31778738" xlink:to="loc_us-gaap_CashSettlementMember_faaed9cd-3d2b-4877-9a14-c667a452c667" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OptionIndexedToIssuersEquityEquityAxis_a7d909da-39e6-4e36-8e15-a8037ef903ca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OptionIndexedToIssuersEquityEquityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4d54cb43-373a-45bf-9f49-769a1fdb0568" xlink:to="loc_us-gaap_OptionIndexedToIssuersEquityEquityAxis_a7d909da-39e6-4e36-8e15-a8037ef903ca" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OptionIndexedToIssuersEquityTypeDomain_a7d909da-39e6-4e36-8e15-a8037ef903ca_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OptionIndexedToIssuersEquityTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_OptionIndexedToIssuersEquityEquityAxis_a7d909da-39e6-4e36-8e15-a8037ef903ca" xlink:to="loc_us-gaap_OptionIndexedToIssuersEquityTypeDomain_a7d909da-39e6-4e36-8e15-a8037ef903ca_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OptionIndexedToIssuersEquityTypeDomain_b691f7f2-8416-43c1-9a27-3be47363c9a8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OptionIndexedToIssuersEquityTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_OptionIndexedToIssuersEquityEquityAxis_a7d909da-39e6-4e36-8e15-a8037ef903ca" xlink:to="loc_us-gaap_OptionIndexedToIssuersEquityTypeDomain_b691f7f2-8416-43c1-9a27-3be47363c9a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CallOptionMember_037004e0-29d9-45cd-9e97-9bd419f4f9c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CallOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OptionIndexedToIssuersEquityTypeDomain_b691f7f2-8416-43c1-9a27-3be47363c9a8" xlink:to="loc_us-gaap_CallOptionMember_037004e0-29d9-45cd-9e97-9bd419f4f9c2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_379cdb50-08f5-4e62-99fa-41f41c598343" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_379cdb50-08f5-4e62-99fa-41f41c598343" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_48b5c620-ece4-469c-b058-609516762e22" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_48b5c620-ece4-469c-b058-609516762e22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromConvertibleDebt_50f618f5-c1a6-4be6-8ece-b1bb5f6684b6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromConvertibleDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:to="loc_us-gaap_ProceedsFromConvertibleDebt_50f618f5-c1a6-4be6-8ece-b1bb5f6684b6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger_45cbeb5a-521b-4cfb-96af-68830068a695" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:to="loc_us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger_45cbeb5a-521b-4cfb-96af-68830068a695" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleThresholdTradingDays_feb34e4b-65df-43b1-a4de-a3b82bfff026" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentConvertibleThresholdTradingDays"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:to="loc_us-gaap_DebtInstrumentConvertibleThresholdTradingDays_feb34e4b-65df-43b1-a4de-a3b82bfff026" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1_bf1f2773-e8e8-4a23-b2fc-39173d4f1e0e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:to="loc_us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1_bf1f2773-e8e8-4a23-b2fc-39173d4f1e0e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed_b14b3254-7ce1-4699-a7ed-37dba6e1a56b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed_b14b3254-7ce1-4699-a7ed-37dba6e1a56b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionRatio1_5054321c-392d-4d48-97c1-2511f6efdd7b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentConvertibleConversionRatio1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionRatio1_5054321c-392d-4d48-97c1-2511f6efdd7b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_6fd6cb00-5a40-4d52-a9c3-bc745f601123" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_6fd6cb00-5a40-4d52-a9c3-bc745f601123" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_DebtInstrumentConvertibleConversionRatioIncrease_2cc98eb9-13d7-43f4-b223-d9e7f9020e5c" xlink:href="mdb-20250430.xsd#mdb_DebtInstrumentConvertibleConversionRatioIncrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:to="loc_mdb_DebtInstrumentConvertibleConversionRatioIncrease_2cc98eb9-13d7-43f4-b223-d9e7f9020e5c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtConversionConvertedInstrumentSharesIssued1_0a385634-d628-47a4-8433-55014396f4d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtConversionConvertedInstrumentSharesIssued1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:to="loc_us-gaap_DebtConversionConvertedInstrumentSharesIssued1_0a385634-d628-47a4-8433-55014396f4d1" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtConversionConvertedInstrumentAmount1_3263e50f-9ce1-42c6-bf3c-e61f2cd0c574" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtConversionConvertedInstrumentAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:to="loc_us-gaap_DebtConversionConvertedInstrumentAmount1_3263e50f-9ce1-42c6-bf3c-e61f2cd0c574" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OptionIndexedToIssuersEquityStrikePrice1_a5149b2e-0ede-449d-a562-8776fe6b1a7e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OptionIndexedToIssuersEquityStrikePrice1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:to="loc_us-gaap_OptionIndexedToIssuersEquityStrikePrice1_a5149b2e-0ede-449d-a562-8776fe6b1a7e" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_OptionIndexedToIssuersEquityCapPrice_2394d487-00ec-4476-a83c-a124931e63d0" xlink:href="mdb-20250430.xsd#mdb_OptionIndexedToIssuersEquityCapPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:to="loc_mdb_OptionIndexedToIssuersEquityCapPrice_2394d487-00ec-4476-a83c-a124931e63d0" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalEquityComponentOfConvertibleDebtSubsequentAdjustments_d280635f-175f-48f4-8fc6-3b45c88ae8b7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalEquityComponentOfConvertibleDebtSubsequentAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalEquityComponentOfConvertibleDebtSubsequentAdjustments_d280635f-175f-48f4-8fc6-3b45c88ae8b7" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCashReceivedOnHedge_56556cd8-063e-4eb5-ba97-7f53f0ab5652" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeCashReceivedOnHedge"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:to="loc_us-gaap_DerivativeCashReceivedOnHedge_56556cd8-063e-4eb5-ba97-7f53f0ab5652" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeGainOnDerivative_5aacc94a-9421-469c-b03f-f389baadf8a0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeGainOnDerivative"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_69bd03ea-2b0a-4f2d-8016-a1ce62672e95" xlink:to="loc_us-gaap_DerivativeGainOnDerivative_5aacc94a-9421-469c-b03f-f389baadf8a0" xlink:type="arc" order="16"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/LeasesNarrativeDetails" xlink:type="simple" xlink:href="mdb-20250430.xsd#LeasesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/LeasesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_e362ce98-d529-481d-b4fb-592c1f984180" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_fbb9d7ff-ef05-4b63-a18e-80cc2eeeee32" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_e362ce98-d529-481d-b4fb-592c1f984180" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_fbb9d7ff-ef05-4b63-a18e-80cc2eeeee32" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_37251d50-2717-4ddf-9ebb-70cfb9bcf44f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_fbb9d7ff-ef05-4b63-a18e-80cc2eeeee32" xlink:to="loc_srt_RangeAxis_37251d50-2717-4ddf-9ebb-70cfb9bcf44f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_37251d50-2717-4ddf-9ebb-70cfb9bcf44f_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_37251d50-2717-4ddf-9ebb-70cfb9bcf44f" xlink:to="loc_srt_RangeMember_37251d50-2717-4ddf-9ebb-70cfb9bcf44f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_7d5510d2-86bb-49d2-9342-01a053d305b4" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_37251d50-2717-4ddf-9ebb-70cfb9bcf44f" xlink:to="loc_srt_RangeMember_7d5510d2-86bb-49d2-9342-01a053d305b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_b7de741e-73cd-4c55-9150-f071b15af7f6" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_7d5510d2-86bb-49d2-9342-01a053d305b4" xlink:to="loc_srt_MinimumMember_b7de741e-73cd-4c55-9150-f071b15af7f6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_a3fb8b99-07ef-4f9d-85b8-aa27a602f5e0" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_7d5510d2-86bb-49d2-9342-01a053d305b4" xlink:to="loc_srt_MaximumMember_a3fb8b99-07ef-4f9d-85b8-aa27a602f5e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_LesseeLeaseTermOfContract_2aea86da-13d6-4c98-b0dc-d741c38aaf76" xlink:href="mdb-20250430.xsd#mdb_LesseeLeaseTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_e362ce98-d529-481d-b4fb-592c1f984180" xlink:to="loc_mdb_LesseeLeaseTermOfContract_2aea86da-13d6-4c98-b0dc-d741c38aaf76" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/RevenueScheduleoftotalrevenuebygeographicareasDetails" xlink:type="simple" xlink:href="mdb-20250430.xsd#RevenueScheduleoftotalrevenuebygeographicareasDetails"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/RevenueScheduleoftotalrevenuebygeographicareasDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_0401f982-26a8-42e8-a06e-a06b0fdc6489" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_1d2d911a-f819-4540-8b7d-260cf50add9f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_0401f982-26a8-42e8-a06e-a06b0fdc6489" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_1d2d911a-f819-4540-8b7d-260cf50add9f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_6ff63f59-be92-493d-8377-5d24422032d6" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_1d2d911a-f819-4540-8b7d-260cf50add9f" xlink:to="loc_srt_StatementGeographicalAxis_6ff63f59-be92-493d-8377-5d24422032d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_6ff63f59-be92-493d-8377-5d24422032d6_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_6ff63f59-be92-493d-8377-5d24422032d6" xlink:to="loc_srt_SegmentGeographicalDomain_6ff63f59-be92-493d-8377-5d24422032d6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_97e05f53-dce9-4284-a6ca-afa9b96cf251" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_6ff63f59-be92-493d-8377-5d24422032d6" xlink:to="loc_srt_SegmentGeographicalDomain_97e05f53-dce9-4284-a6ca-afa9b96cf251" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AmericasMember_69eacf1e-aadc-4a98-baef-b16336d60e02" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_AmericasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_97e05f53-dce9-4284-a6ca-afa9b96cf251" xlink:to="loc_srt_AmericasMember_69eacf1e-aadc-4a98-baef-b16336d60e02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EMEAMember_668a9ee8-4232-4cdd-a69a-d04be94d6036" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EMEAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_97e05f53-dce9-4284-a6ca-afa9b96cf251" xlink:to="loc_us-gaap_EMEAMember_668a9ee8-4232-4cdd-a69a-d04be94d6036" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AsiaPacificMember_35120200-e3a4-4d97-a44a-8e3157dbaf29" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_AsiaPacificMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_97e05f53-dce9-4284-a6ca-afa9b96cf251" xlink:to="loc_srt_AsiaPacificMember_35120200-e3a4-4d97-a44a-8e3157dbaf29" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_1d2ae36e-9803-4f4f-921a-e3e57576e759" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_1d2d911a-f819-4540-8b7d-260cf50add9f" xlink:to="loc_srt_ProductOrServiceAxis_1d2ae36e-9803-4f4f-921a-e3e57576e759" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_1d2ae36e-9803-4f4f-921a-e3e57576e759_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_1d2ae36e-9803-4f4f-921a-e3e57576e759" xlink:to="loc_srt_ProductsAndServicesDomain_1d2ae36e-9803-4f4f-921a-e3e57576e759_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_e9c1344b-ac2c-4afc-b6bd-34d9cd428577" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_1d2ae36e-9803-4f4f-921a-e3e57576e759" xlink:to="loc_srt_ProductsAndServicesDomain_e9c1344b-ac2c-4afc-b6bd-34d9cd428577" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_MongoDBAtlasRelatedMember_c1009c7e-efe9-421a-8ea5-b817273caea1" xlink:href="mdb-20250430.xsd#mdb_MongoDBAtlasRelatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e9c1344b-ac2c-4afc-b6bd-34d9cd428577" xlink:to="loc_mdb_MongoDBAtlasRelatedMember_c1009c7e-efe9-421a-8ea5-b817273caea1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_OtherSubscriptionMember_00accaaf-7509-43b7-8678-893639ead320" xlink:href="mdb-20250430.xsd#mdb_OtherSubscriptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e9c1344b-ac2c-4afc-b6bd-34d9cd428577" xlink:to="loc_mdb_OtherSubscriptionMember_00accaaf-7509-43b7-8678-893639ead320" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceMember_ef8eb281-ac5b-426d-87de-b369be25735e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e9c1344b-ac2c-4afc-b6bd-34d9cd428577" xlink:to="loc_us-gaap_ServiceMember_ef8eb281-ac5b-426d-87de-b369be25735e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_fa9284d7-5007-4200-ac98-62614a9c4b81" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_0401f982-26a8-42e8-a06e-a06b0fdc6489" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_fa9284d7-5007-4200-ac98-62614a9c4b81" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/RevenueAdditionalInformationDetails" xlink:type="simple" xlink:href="mdb-20250430.xsd#RevenueAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/RevenueAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_809873fc-f37f-4d2e-9526-0d505397a83b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_809873fc-f37f-4d2e-9526-0d505397a83b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_c3b445f1-12a9-41ff-9598-2043bfd1bb1e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_809873fc-f37f-4d2e-9526-0d505397a83b" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_c3b445f1-12a9-41ff-9598-2043bfd1bb1e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_ff4bf247-8e99-42c8-a66d-fcfc3afcc604" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_809873fc-f37f-4d2e-9526-0d505397a83b" xlink:to="loc_srt_RangeAxis_ff4bf247-8e99-42c8-a66d-fcfc3afcc604" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ff4bf247-8e99-42c8-a66d-fcfc3afcc604_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_ff4bf247-8e99-42c8-a66d-fcfc3afcc604" xlink:to="loc_srt_RangeMember_ff4bf247-8e99-42c8-a66d-fcfc3afcc604_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a6cae0dc-9510-40a4-900b-7a18e760fc74" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_ff4bf247-8e99-42c8-a66d-fcfc3afcc604" xlink:to="loc_srt_RangeMember_a6cae0dc-9510-40a4-900b-7a18e760fc74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_a5c72a7d-2193-488b-8a91-c7bdbfb37b7e" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a6cae0dc-9510-40a4-900b-7a18e760fc74" xlink:to="loc_srt_MinimumMember_a5c72a7d-2193-488b-8a91-c7bdbfb37b7e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_ee251211-37bd-4def-be4b-8209c100f3e7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a6cae0dc-9510-40a4-900b-7a18e760fc74" xlink:to="loc_srt_MaximumMember_ee251211-37bd-4def-be4b-8209c100f3e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_f0d0a798-e661-4f8e-99a6-631f117dc098" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_ContractWithCustomerLiability_f0d0a798-e661-4f8e-99a6-631f117dc098" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_ContractWithCustomerLiabilityRevenueRecognizedPercent_947da589-5313-40cb-ac23-1f3216c4a819" xlink:href="mdb-20250430.xsd#mdb_ContractWithCustomerLiabilityRevenueRecognizedPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_mdb_ContractWithCustomerLiabilityRevenueRecognizedPercent_947da589-5313-40cb-ac23-1f3216c4a819" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_da1c0b41-44f2-4918-8fb3-64311027e77c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_da1c0b41-44f2-4918-8fb3-64311027e77c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_04d403ed-6fbe-42dd-b9cf-43c6893a0616" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_04d403ed-6fbe-42dd-b9cf-43c6893a0616" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_456b36d6-3ff3-41db-84fa-3788a4e9677e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_456b36d6-3ff3-41db-84fa-3788a4e9677e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetNetCurrent_a4dd2d44-7d37-4b83-a753-f46df9da01b3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerAssetNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_ContractWithCustomerAssetNetCurrent_a4dd2d44-7d37-4b83-a753-f46df9da01b3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostNet_7bb64aa8-b441-4a97-ab69-22306c82b5d2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CapitalizedContractCostNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_CapitalizedContractCostNet_7bb64aa8-b441-4a97-ab69-22306c82b5d2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostNetNoncurrent_3d625dc1-cc12-4b3b-95e1-9185543c2a07" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CapitalizedContractCostNetNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_CapitalizedContractCostNetNoncurrent_3d625dc1-cc12-4b3b-95e1-9185543c2a07" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostAmortization_edcc5f56-acbe-4008-8d9a-8c85b91ec067" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CapitalizedContractCostAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_CapitalizedContractCostAmortization_edcc5f56-acbe-4008-8d9a-8c85b91ec067" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostImpairmentLoss_566054da-af0b-4bdb-93f2-c88a8c02d138" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CapitalizedContractCostImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_CapitalizedContractCostImpairmentLoss_566054da-af0b-4bdb-93f2-c88a8c02d138" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/RevenueAdditionalInformationDetails_1" xlink:type="simple" xlink:href="mdb-20250430.xsd#RevenueAdditionalInformationDetails_1"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/RevenueAdditionalInformationDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_809873fc-f37f-4d2e-9526-0d505397a83b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_809873fc-f37f-4d2e-9526-0d505397a83b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_ff4bf247-8e99-42c8-a66d-fcfc3afcc604" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_809873fc-f37f-4d2e-9526-0d505397a83b" xlink:to="loc_srt_RangeAxis_ff4bf247-8e99-42c8-a66d-fcfc3afcc604" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ff4bf247-8e99-42c8-a66d-fcfc3afcc604_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_ff4bf247-8e99-42c8-a66d-fcfc3afcc604" xlink:to="loc_srt_RangeMember_ff4bf247-8e99-42c8-a66d-fcfc3afcc604_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a6cae0dc-9510-40a4-900b-7a18e760fc74" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_ff4bf247-8e99-42c8-a66d-fcfc3afcc604" xlink:to="loc_srt_RangeMember_a6cae0dc-9510-40a4-900b-7a18e760fc74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_a5c72a7d-2193-488b-8a91-c7bdbfb37b7e" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a6cae0dc-9510-40a4-900b-7a18e760fc74" xlink:to="loc_srt_MinimumMember_a5c72a7d-2193-488b-8a91-c7bdbfb37b7e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_ee251211-37bd-4def-be4b-8209c100f3e7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a6cae0dc-9510-40a4-900b-7a18e760fc74" xlink:to="loc_srt_MaximumMember_ee251211-37bd-4def-be4b-8209c100f3e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_f0d0a798-e661-4f8e-99a6-631f117dc098" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_ContractWithCustomerLiability_f0d0a798-e661-4f8e-99a6-631f117dc098" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_ContractWithCustomerLiabilityRevenueRecognizedPercent_947da589-5313-40cb-ac23-1f3216c4a819" xlink:href="mdb-20250430.xsd#mdb_ContractWithCustomerLiabilityRevenueRecognizedPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_mdb_ContractWithCustomerLiabilityRevenueRecognizedPercent_947da589-5313-40cb-ac23-1f3216c4a819" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_da1c0b41-44f2-4918-8fb3-64311027e77c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_da1c0b41-44f2-4918-8fb3-64311027e77c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_04d403ed-6fbe-42dd-b9cf-43c6893a0616" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_04d403ed-6fbe-42dd-b9cf-43c6893a0616" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_456b36d6-3ff3-41db-84fa-3788a4e9677e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_456b36d6-3ff3-41db-84fa-3788a4e9677e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetNetCurrent_a4dd2d44-7d37-4b83-a753-f46df9da01b3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerAssetNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_ContractWithCustomerAssetNetCurrent_a4dd2d44-7d37-4b83-a753-f46df9da01b3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostNet_7bb64aa8-b441-4a97-ab69-22306c82b5d2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CapitalizedContractCostNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_CapitalizedContractCostNet_7bb64aa8-b441-4a97-ab69-22306c82b5d2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostNetNoncurrent_3d625dc1-cc12-4b3b-95e1-9185543c2a07" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CapitalizedContractCostNetNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_CapitalizedContractCostNetNoncurrent_3d625dc1-cc12-4b3b-95e1-9185543c2a07" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostAmortization_edcc5f56-acbe-4008-8d9a-8c85b91ec067" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CapitalizedContractCostAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_CapitalizedContractCostAmortization_edcc5f56-acbe-4008-8d9a-8c85b91ec067" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostImpairmentLoss_566054da-af0b-4bdb-93f2-c88a8c02d138" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CapitalizedContractCostImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5a930097-72ff-4e27-b816-0403c66506a0" xlink:to="loc_us-gaap_CapitalizedContractCostImpairmentLoss_566054da-af0b-4bdb-93f2-c88a8c02d138" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/EquityScheduleofStockActivityDetails" xlink:type="simple" xlink:href="mdb-20250430.xsd#EquityScheduleofStockActivityDetails"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/EquityScheduleofStockActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5adc08fd-60a0-4882-94da-f59c231802f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9446c777-1611-4f86-b32c-1326f86dd5ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5adc08fd-60a0-4882-94da-f59c231802f0" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9446c777-1611-4f86-b32c-1326f86dd5ff" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_01f1a7e1-ba8f-4174-af38-b9f1aa93f055" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9446c777-1611-4f86-b32c-1326f86dd5ff" xlink:to="loc_us-gaap_AwardTypeAxis_01f1a7e1-ba8f-4174-af38-b9f1aa93f055" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01f1a7e1-ba8f-4174-af38-b9f1aa93f055_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_01f1a7e1-ba8f-4174-af38-b9f1aa93f055" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01f1a7e1-ba8f-4174-af38-b9f1aa93f055_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_98ac047f-889d-4571-9a4c-d744f8bee055" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_01f1a7e1-ba8f-4174-af38-b9f1aa93f055" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_98ac047f-889d-4571-9a4c-d744f8bee055" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_8a67cfa1-27b5-45f0-a2b1-56161db41eb1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_98ac047f-889d-4571-9a4c-d744f8bee055" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_8a67cfa1-27b5-45f0-a2b1-56161db41eb1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_ebdd8627-12d1-43ad-a655-a2326e6727bc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_98ac047f-889d-4571-9a4c-d744f8bee055" xlink:to="loc_us-gaap_RestrictedStockMember_ebdd8627-12d1-43ad-a655-a2326e6727bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_a9be2198-5073-4bc7-b472-61d764b6ff1c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_98ac047f-889d-4571-9a4c-d744f8bee055" xlink:to="loc_us-gaap_PerformanceSharesMember_a9be2198-5073-4bc7-b472-61d764b6ff1c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6f74ea7e-9c47-48f2-a38c-3ecf9d83a7e5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5adc08fd-60a0-4882-94da-f59c231802f0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6f74ea7e-9c47-48f2-a38c-3ecf9d83a7e5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_927bd7e6-7947-4b5d-a7db-d8e5a45a7040" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6f74ea7e-9c47-48f2-a38c-3ecf9d83a7e5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_927bd7e6-7947-4b5d-a7db-d8e5a45a7040" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_0664562d-229c-49fe-9dcf-950c6435f0b9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6f74ea7e-9c47-48f2-a38c-3ecf9d83a7e5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_0664562d-229c-49fe-9dcf-950c6435f0b9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_cbb1d042-943e-4a4f-a19c-128e30f9af59" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6f74ea7e-9c47-48f2-a38c-3ecf9d83a7e5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_cbb1d042-943e-4a4f-a19c-128e30f9af59" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPeriodIncreaseDecrease_3140c2ab-c8e6-4a33-a9a7-d20296ed0d51" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6f74ea7e-9c47-48f2-a38c-3ecf9d83a7e5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPeriodIncreaseDecrease_3140c2ab-c8e6-4a33-a9a7-d20296ed0d51" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_c516b209-fbdf-4cc6-8804-f9ef2bfade97" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6f74ea7e-9c47-48f2-a38c-3ecf9d83a7e5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_c516b209-fbdf-4cc6-8804-f9ef2bfade97" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_b45ac692-42e6-40c2-8871-9746e8e1169d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_4a5db31e-49e3-4729-8abb-6c450d948519" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5adc08fd-60a0-4882-94da-f59c231802f0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_4a5db31e-49e3-4729-8abb-6c450d948519" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_fb431927-d13a-4b2f-8565-0594ebd6036f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_4a5db31e-49e3-4729-8abb-6c450d948519" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_fb431927-d13a-4b2f-8565-0594ebd6036f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_009c7170-8cf7-4e0b-915c-7448ec3d7456" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_4a5db31e-49e3-4729-8abb-6c450d948519" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_009c7170-8cf7-4e0b-915c-7448ec3d7456" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_12f79fdb-350b-44c4-9060-20e975595a39" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_4a5db31e-49e3-4729-8abb-6c450d948519" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_12f79fdb-350b-44c4-9060-20e975595a39" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPeriodAdjustmentsWeightedAverageGrantDateFairValue_76150d26-b2c7-4ed5-82d8-ac3b5d35db4e" xlink:href="mdb-20250430.xsd#mdb_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPeriodAdjustmentsWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_4a5db31e-49e3-4729-8abb-6c450d948519" xlink:to="loc_mdb_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPeriodAdjustmentsWeightedAverageGrantDateFairValue_76150d26-b2c7-4ed5-82d8-ac3b5d35db4e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_61f16b6e-1cc8-4813-badf-35155452fccb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_4a5db31e-49e3-4729-8abb-6c450d948519" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_61f16b6e-1cc8-4813-badf-35155452fccb" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_ad60bf03-0b85-4fe6-b96e-0238843d8585" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/EquityAdditionalInformationDetails" xlink:type="simple" xlink:href="mdb-20250430.xsd#EquityAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/EquityAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_14cb050a-74c5-4ba5-b93d-710bd9bbb92f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_378abcd3-b80d-4c71-9996-48c7f33f3a68" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_14cb050a-74c5-4ba5-b93d-710bd9bbb92f" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_378abcd3-b80d-4c71-9996-48c7f33f3a68" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_309b2e77-d16f-4644-8e10-5398014e0b1d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_378abcd3-b80d-4c71-9996-48c7f33f3a68" xlink:to="loc_us-gaap_AwardTypeAxis_309b2e77-d16f-4644-8e10-5398014e0b1d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_309b2e77-d16f-4644-8e10-5398014e0b1d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_309b2e77-d16f-4644-8e10-5398014e0b1d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_309b2e77-d16f-4644-8e10-5398014e0b1d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a115ebd9-1884-440e-ac1a-542100ec05d6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_309b2e77-d16f-4644-8e10-5398014e0b1d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a115ebd9-1884-440e-ac1a-542100ec05d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_e5543877-9a8d-477f-941e-00639418240c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a115ebd9-1884-440e-ac1a-542100ec05d6" xlink:to="loc_us-gaap_EmployeeStockMember_e5543877-9a8d-477f-941e-00639418240c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_72987395-faad-4b02-b6eb-05a6e7573e10" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_378abcd3-b80d-4c71-9996-48c7f33f3a68" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_72987395-faad-4b02-b6eb-05a6e7573e10" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_72987395-faad-4b02-b6eb-05a6e7573e10_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_72987395-faad-4b02-b6eb-05a6e7573e10" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_72987395-faad-4b02-b6eb-05a6e7573e10_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_e509dc55-716d-4978-8511-ca723a744645" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_72987395-faad-4b02-b6eb-05a6e7573e10" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_e509dc55-716d-4978-8511-ca723a744645" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_f46a4beb-1a08-427d-a830-bb3b49003d95" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_e509dc55-716d-4978-8511-ca723a744645" xlink:to="loc_us-gaap_SubsequentEventMember_f46a4beb-1a08-427d-a830-bb3b49003d95" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate_bbe1b6c1-1081-4f0b-98fd-e96df2efabc8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_14cb050a-74c5-4ba5-b93d-710bd9bbb92f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate_bbe1b6c1-1081-4f0b-98fd-e96df2efabc8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramAuthorizedAmount1_c5183a2f-1f95-4d63-8841-b4874cff76ff" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_14cb050a-74c5-4ba5-b93d-710bd9bbb92f" xlink:to="loc_srt_StockRepurchaseProgramAuthorizedAmount1_c5183a2f-1f95-4d63-8841-b4874cff76ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonValue_4b8fb263-2a99-4084-8020-f01e4dd16270" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_14cb050a-74c5-4ba5-b93d-710bd9bbb92f" xlink:to="loc_us-gaap_TreasuryStockCommonValue_4b8fb263-2a99-4084-8020-f01e4dd16270" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/EquityStockbasedCompensationExpenseRecognizedinStatementofOperationsDetails" xlink:type="simple" xlink:href="mdb-20250430.xsd#EquityStockbasedCompensationExpenseRecognizedinStatementofOperationsDetails"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/EquityStockbasedCompensationExpenseRecognizedinStatementofOperationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7a202317-69d6-448d-9755-36349713e9d6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f9cb074e-c342-49a3-ba13-5c1c205fd52d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7a202317-69d6-448d-9755-36349713e9d6" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f9cb074e-c342-49a3-ba13-5c1c205fd52d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_9b9f9bba-b9d8-4fcc-bda3-e69f4d13d434" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f9cb074e-c342-49a3-ba13-5c1c205fd52d" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_9b9f9bba-b9d8-4fcc-bda3-e69f4d13d434" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_9b9f9bba-b9d8-4fcc-bda3-e69f4d13d434_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_9b9f9bba-b9d8-4fcc-bda3-e69f4d13d434" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_9b9f9bba-b9d8-4fcc-bda3-e69f4d13d434_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_995f754a-afb9-4fc4-9b0a-38e39c6cfa42" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_9b9f9bba-b9d8-4fcc-bda3-e69f4d13d434" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_995f754a-afb9-4fc4-9b0a-38e39c6cfa42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_CostofRevenueSubscriptionMember_7e9ca1b4-4486-43d8-a22c-2e79c89eccff" xlink:href="mdb-20250430.xsd#mdb_CostofRevenueSubscriptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_995f754a-afb9-4fc4-9b0a-38e39c6cfa42" xlink:to="loc_mdb_CostofRevenueSubscriptionMember_7e9ca1b4-4486-43d8-a22c-2e79c89eccff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_CostofRevenueServicesMember_44abf20b-7fb9-4bb9-91d5-5335ad07fc10" xlink:href="mdb-20250430.xsd#mdb_CostofRevenueServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_995f754a-afb9-4fc4-9b0a-38e39c6cfa42" xlink:to="loc_mdb_CostofRevenueServicesMember_44abf20b-7fb9-4bb9-91d5-5335ad07fc10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpenseMember_d2dbc090-f2ab-450d-bc0d-19a3cba8b3cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingAndMarketingExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_995f754a-afb9-4fc4-9b0a-38e39c6cfa42" xlink:to="loc_us-gaap_SellingAndMarketingExpenseMember_d2dbc090-f2ab-450d-bc0d-19a3cba8b3cd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_1397e0f1-31c0-4c84-b344-109ddf11ccd5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_995f754a-afb9-4fc4-9b0a-38e39c6cfa42" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_1397e0f1-31c0-4c84-b344-109ddf11ccd5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_fd11dee0-3fa8-4538-8ee6-a56502a9a139" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeneralAndAdministrativeExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_995f754a-afb9-4fc4-9b0a-38e39c6cfa42" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_fd11dee0-3fa8-4538-8ee6-a56502a9a139" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_4bff8f37-0572-46e0-b1c3-a689f18b2490" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7a202317-69d6-448d-9755-36349713e9d6" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_4bff8f37-0572-46e0-b1c3-a689f18b2490" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/NetLossPerShareScheduleofAntidilutiveSecuritiesExcludedfromtheComputationofDilutedNetLossperShareDetails" xlink:type="simple" xlink:href="mdb-20250430.xsd#NetLossPerShareScheduleofAntidilutiveSecuritiesExcludedfromtheComputationofDilutedNetLossperShareDetails"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/NetLossPerShareScheduleofAntidilutiveSecuritiesExcludedfromtheComputationofDilutedNetLossperShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_53e45a80-1552-4106-885b-022f4031ac5f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_199adb05-07a5-4701-bdb5-b3146a73bdd5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_53e45a80-1552-4106-885b-022f4031ac5f" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_199adb05-07a5-4701-bdb5-b3146a73bdd5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_54852607-170c-41b1-bef1-64bb14a836f9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_199adb05-07a5-4701-bdb5-b3146a73bdd5" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_54852607-170c-41b1-bef1-64bb14a836f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_54852607-170c-41b1-bef1-64bb14a836f9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_54852607-170c-41b1-bef1-64bb14a836f9" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_54852607-170c-41b1-bef1-64bb14a836f9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_e059df41-6285-44ca-a309-4127b18182c6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_54852607-170c-41b1-bef1-64bb14a836f9" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_e059df41-6285-44ca-a309-4127b18182c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_bb0b15a7-02d0-4e53-a33f-ce92e1627c63" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_e059df41-6285-44ca-a309-4127b18182c6" xlink:to="loc_us-gaap_EmployeeStockOptionMember_bb0b15a7-02d0-4e53-a33f-ce92e1627c63" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_f209690b-adf9-4268-a595-becd800ff5ea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_e059df41-6285-44ca-a309-4127b18182c6" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_f209690b-adf9-4268-a595-becd800ff5ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_aca0719e-41fd-4ba8-bfc0-08425888a0c1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_e059df41-6285-44ca-a309-4127b18182c6" xlink:to="loc_us-gaap_RestrictedStockMember_aca0719e-41fd-4ba8-bfc0-08425888a0c1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_d03c01f7-ef4d-4169-a30b-0b57a2586e54" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_e059df41-6285-44ca-a309-4127b18182c6" xlink:to="loc_us-gaap_PerformanceSharesMember_d03c01f7-ef4d-4169-a30b-0b57a2586e54" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtSecuritiesMember_b5abe9fc-f55b-4d5c-85d9-99dfef6f344f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConvertibleDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_e059df41-6285-44ca-a309-4127b18182c6" xlink:to="loc_us-gaap_ConvertibleDebtSecuritiesMember_b5abe9fc-f55b-4d5c-85d9-99dfef6f344f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_75bc2bc3-f484-4ac5-a2d3-49d0a8ab62ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_199adb05-07a5-4701-bdb5-b3146a73bdd5" xlink:to="loc_us-gaap_StatementClassOfStockAxis_75bc2bc3-f484-4ac5-a2d3-49d0a8ab62ba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_75bc2bc3-f484-4ac5-a2d3-49d0a8ab62ba_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_75bc2bc3-f484-4ac5-a2d3-49d0a8ab62ba" xlink:to="loc_us-gaap_ClassOfStockDomain_75bc2bc3-f484-4ac5-a2d3-49d0a8ab62ba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_74c047c2-e718-4385-99d5-22bff801cb29" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_75bc2bc3-f484-4ac5-a2d3-49d0a8ab62ba" xlink:to="loc_us-gaap_ClassOfStockDomain_74c047c2-e718-4385-99d5-22bff801cb29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_68c02057-7e98-4ed1-b7ec-20264f905576" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_74c047c2-e718-4385-99d5-22bff801cb29" xlink:to="loc_us-gaap_CommonClassAMember_68c02057-7e98-4ed1-b7ec-20264f905576" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassBMember_1b4eea4a-f25b-4ccf-9e15-e5a62680760a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonClassBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_74c047c2-e718-4385-99d5-22bff801cb29" xlink:to="loc_us-gaap_CommonClassBMember_1b4eea4a-f25b-4ccf-9e15-e5a62680760a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_c893f04a-d392-4e0b-a903-615356c1cd84" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_199adb05-07a5-4701-bdb5-b3146a73bdd5" xlink:to="loc_us-gaap_DebtInstrumentAxis_c893f04a-d392-4e0b-a903-615356c1cd84" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_c893f04a-d392-4e0b-a903-615356c1cd84_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_c893f04a-d392-4e0b-a903-615356c1cd84" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_c893f04a-d392-4e0b-a903-615356c1cd84_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_230a6f05-8b21-4fb0-b9b8-6a69f8d048f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_c893f04a-d392-4e0b-a903-615356c1cd84" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_230a6f05-8b21-4fb0-b9b8-6a69f8d048f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_ConvertibleNotesDue2026Member_1f59a1d2-febf-47ed-aed7-c35f2db3f1a0" xlink:href="mdb-20250430.xsd#mdb_ConvertibleNotesDue2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_230a6f05-8b21-4fb0-b9b8-6a69f8d048f0" xlink:to="loc_mdb_ConvertibleNotesDue2026Member_1f59a1d2-febf-47ed-aed7-c35f2db3f1a0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_2710c300-500f-4d1b-90f3-711cbd16eb14" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_53e45a80-1552-4106-885b-022f4031ac5f" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_2710c300-500f-4d1b-90f3-711cbd16eb14" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.mongodb.com/role/SegmentReportingDetails" xlink:type="simple" xlink:href="mdb-20250430.xsd#SegmentReportingDetails"/>
  <link:definitionLink xlink:role="http://www.mongodb.com/role/SegmentReportingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_c4dd2150-56fb-4f69-9c76-04df93642c9c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_7876ec62-abe3-4331-9fc9-2d7e47983e54" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_c4dd2150-56fb-4f69-9c76-04df93642c9c" xlink:to="loc_us-gaap_ConcentrationRiskTable_7876ec62-abe3-4331-9fc9-2d7e47983e54" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_cab04ece-eabd-4f91-a0ad-cb5d252c5ad4" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_7876ec62-abe3-4331-9fc9-2d7e47983e54" xlink:to="loc_srt_StatementGeographicalAxis_cab04ece-eabd-4f91-a0ad-cb5d252c5ad4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_cab04ece-eabd-4f91-a0ad-cb5d252c5ad4_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_cab04ece-eabd-4f91-a0ad-cb5d252c5ad4" xlink:to="loc_srt_SegmentGeographicalDomain_cab04ece-eabd-4f91-a0ad-cb5d252c5ad4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_359490a2-785e-42d9-a2d4-37b167780857" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_cab04ece-eabd-4f91-a0ad-cb5d252c5ad4" xlink:to="loc_srt_SegmentGeographicalDomain_359490a2-785e-42d9-a2d4-37b167780857" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_1f0b5fcf-7ae6-4b27-83a3-6efe6634cdc4" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_359490a2-785e-42d9-a2d4-37b167780857" xlink:to="loc_country_US_1f0b5fcf-7ae6-4b27-83a3-6efe6634cdc4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_IE_47819db4-fe09-4089-a42c-83f336c3c219" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_IE"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_359490a2-785e-42d9-a2d4-37b167780857" xlink:to="loc_country_IE_47819db4-fe09-4089-a42c-83f336c3c219" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_dc08e737-d361-44f9-b2d4-245b758aba41" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_7876ec62-abe3-4331-9fc9-2d7e47983e54" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_dc08e737-d361-44f9-b2d4-245b758aba41" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_dc08e737-d361-44f9-b2d4-245b758aba41_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_dc08e737-d361-44f9-b2d4-245b758aba41" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_dc08e737-d361-44f9-b2d4-245b758aba41_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_1be60609-d7c1-41e8-865b-1e29d699a9a0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_dc08e737-d361-44f9-b2d4-245b758aba41" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_1be60609-d7c1-41e8-865b-1e29d699a9a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesRevenueNetMember_45143d5f-50f9-4a1d-a48a-adb968102aea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SalesRevenueNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_1be60609-d7c1-41e8-865b-1e29d699a9a0" xlink:to="loc_us-gaap_SalesRevenueNetMember_45143d5f-50f9-4a1d-a48a-adb968102aea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_mdb_LongLivedAssetBenchmarkMember_c34b401f-4cbf-4192-9299-3c249f16f422" xlink:href="mdb-20250430.xsd#mdb_LongLivedAssetBenchmarkMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_1be60609-d7c1-41e8-865b-1e29d699a9a0" xlink:to="loc_mdb_LongLivedAssetBenchmarkMember_c34b401f-4cbf-4192-9299-3c249f16f422" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_477cf3e4-65a2-427c-bf33-d175742ddb0f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_7876ec62-abe3-4331-9fc9-2d7e47983e54" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_477cf3e4-65a2-427c-bf33-d175742ddb0f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_477cf3e4-65a2-427c-bf33-d175742ddb0f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_477cf3e4-65a2-427c-bf33-d175742ddb0f" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_477cf3e4-65a2-427c-bf33-d175742ddb0f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_1a36d843-9b20-4523-8160-bd3bbeab4eb7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_477cf3e4-65a2-427c-bf33-d175742ddb0f" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_1a36d843-9b20-4523-8160-bd3bbeab4eb7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicConcentrationRiskMember_21a76ab0-204b-4b26-8e46-29896483a888" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeographicConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_1a36d843-9b20-4523-8160-bd3bbeab4eb7" xlink:to="loc_us-gaap_GeographicConcentrationRiskMember_21a76ab0-204b-4b26-8e46-29896483a888" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_0c3e30d2-1524-41c4-a5ab-1f1527c1f701" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_c4dd2150-56fb-4f69-9c76-04df93642c9c" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_0c3e30d2-1524-41c4-a5ab-1f1527c1f701" xlink:type="arc" order="0"/>
  </link:definitionLink>
</link:linkbase>
