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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019fceb7-6595-797c-abae-b46e9f9861c1,g:08fbfc52-cf72-4fd2-a091-c4da7d018c01-->
<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.arvinas.com/role/CondensedConsolidatedStatementsofChangesinStockholdersEquityunaudited" xlink:type="simple" xlink:href="arvn-20260930.xsd#CondensedConsolidatedStatementsofChangesinStockholdersEquityunaudited"/>
  <link:definitionLink xlink:role="http://www.arvinas.com/role/CondensedConsolidatedStatementsofChangesinStockholdersEquityunaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019fceb7-6632-7a87-aeec-5b8b6db16d75" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019fceb7-6632-74cb-8908-d28280056a93" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019fceb7-6632-7a87-aeec-5b8b6db16d75" xlink:to="loc_us-gaap_StatementTable_019fceb7-6632-74cb-8908-d28280056a93" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019fceb7-6632-7a4b-8ec6-7ca561d74108" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019fceb7-6632-74cb-8908-d28280056a93" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019fceb7-6632-7a4b-8ec6-7ca561d74108" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019fceb7-6632-7a4b-8ec6-7ca561d74108_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019fceb7-6632-7a4b-8ec6-7ca561d74108" xlink:to="loc_us-gaap_EquityComponentDomain_019fceb7-6632-7a4b-8ec6-7ca561d74108_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019fceb7-6632-7e0f-8ed7-97a93e616c6a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019fceb7-6632-7a4b-8ec6-7ca561d74108" xlink:to="loc_us-gaap_EquityComponentDomain_019fceb7-6632-7e0f-8ed7-97a93e616c6a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019fceb7-6632-7547-a99b-726d290dacf7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019fceb7-6632-7e0f-8ed7-97a93e616c6a" xlink:to="loc_us-gaap_CommonStockMember_019fceb7-6632-7547-a99b-726d290dacf7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019fceb7-6632-7db2-941e-56e3ae936e82" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019fceb7-6632-7e0f-8ed7-97a93e616c6a" xlink:to="loc_us-gaap_RetainedEarningsMember_019fceb7-6632-7db2-941e-56e3ae936e82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019fceb7-6632-7e2c-acba-3a9c1477af65" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019fceb7-6632-7e0f-8ed7-97a93e616c6a" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019fceb7-6632-7e2c-acba-3a9c1477af65" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019fceb7-6632-7745-bf04-f823a75de777" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019fceb7-6632-7e0f-8ed7-97a93e616c6a" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019fceb7-6632-7745-bf04-f823a75de777" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_019fceb7-6632-7b98-b2ee-585fdb1a8d42" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019fceb7-6632-7e0f-8ed7-97a93e616c6a" xlink:to="loc_us-gaap_TreasuryStockCommonMember_019fceb7-6632-7b98-b2ee-585fdb1a8d42" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fceb7-6632-7842-a619-c0045ee9da64" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019fceb7-6632-7a87-aeec-5b8b6db16d75" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fceb7-6632-7842-a619-c0045ee9da64" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019fceb7-6632-7de9-901a-dc99fc4d67ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fceb7-6632-7842-a619-c0045ee9da64" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_019fceb7-6632-7de9-901a-dc99fc4d67ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_019fceb7-6632-7677-9469-f24492aca9f0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fceb7-6632-7842-a619-c0045ee9da64" xlink:to="loc_us-gaap_TreasuryStockCommonShares_019fceb7-6632-7677-9469-f24492aca9f0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019fceb7-6632-7a04-a56d-666af7be2d74" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fceb7-6632-7842-a619-c0045ee9da64" xlink:to="loc_us-gaap_StockholdersEquity_019fceb7-6632-7a04-a56d-666af7be2d74" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019fceb7-6632-7c08-8317-a1eebd8e5162" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fceb7-6632-7842-a619-c0045ee9da64" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019fceb7-6632-7c08-8317-a1eebd8e5162" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019fceb7-6632-74f2-9867-de5738f0c9c8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fceb7-6632-7842-a619-c0045ee9da64" xlink:to="loc_us-gaap_NetIncomeLoss_019fceb7-6632-74f2-9867-de5738f0c9c8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019fceb7-6632-7e2e-a946-b818f69f7964" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fceb7-6632-7842-a619-c0045ee9da64" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019fceb7-6632-7e2e-a946-b818f69f7964" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationGross_019fceb7-6632-74a2-8bbf-8d5e28c64ff6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fceb7-6632-7842-a619-c0045ee9da64" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationGross_019fceb7-6632-74a2-8bbf-8d5e28c64ff6" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_019fceb7-6632-70a4-b1fc-c7783a250cf5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fceb7-6632-7842-a619-c0045ee9da64" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_019fceb7-6632-70a4-b1fc-c7783a250cf5" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_01a1551c-e9da-79af-ad4f-ee308f24ffdf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fceb7-6632-7842-a619-c0045ee9da64" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_01a1551c-e9da-79af-ad4f-ee308f24ffdf" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_01a1551d-4a0f-7dc1-8cac-c523e1078a57" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fceb7-6632-7842-a619-c0045ee9da64" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_01a1551d-4a0f-7dc1-8cac-c523e1078a57" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent_019fceb7-6632-758a-ba59-55dd8746051c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019fceb7-6632-7842-a619-c0045ee9da64" xlink:to="loc_us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent_019fceb7-6632-758a-ba59-55dd8746051c" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019fceb7-6632-72db-9bfc-70d7d0fbf5ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_019fceb7-6632-70b6-ad0c-a4765203b5a0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019fceb7-6632-7d6f-9518-787363743ce0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.arvinas.com/role/NatureofBusinessandBasisofPresentationDetails" xlink:type="simple" xlink:href="arvn-20260930.xsd#NatureofBusinessandBasisofPresentationDetails"/>
  <link:definitionLink xlink:role="http://www.arvinas.com/role/NatureofBusinessandBasisofPresentationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_01a17d4e-8af5-7898-8387-797dde94ca4b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_01a17d4e-8af5-77d3-b943-e80c92caa9d0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_01a17d4e-8af5-7898-8387-797dde94ca4b" xlink:to="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_01a17d4e-8af5-77d3-b943-e80c92caa9d0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_01a17d4e-8af5-7d4d-9fde-8a56dd10507f" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_01a17d4e-8af5-77d3-b943-e80c92caa9d0" xlink:to="loc_srt_CounterpartyNameAxis_01a17d4e-8af5-7d4d-9fde-8a56dd10507f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_01a17d4e-8af5-7d4d-9fde-8a56dd10507f_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_01a17d4e-8af5-7d4d-9fde-8a56dd10507f" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_01a17d4e-8af5-7d4d-9fde-8a56dd10507f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_01a17d4e-8af5-7f92-87d4-73ac3d2335fd" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_01a17d4e-8af5-7d4d-9fde-8a56dd10507f" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_01a17d4e-8af5-7f92-87d4-73ac3d2335fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_RigelPharmaceuticalsInc.Member_01a17d4e-8af5-7a33-ba61-37ccc0b1bc96" xlink:href="arvn-20260930.xsd#arvn_RigelPharmaceuticalsInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_01a17d4e-8af5-7f92-87d4-73ac3d2335fd" xlink:to="loc_arvn_RigelPharmaceuticalsInc.Member_01a17d4e-8af5-7a33-ba61-37ccc0b1bc96" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_01a17d4e-8af5-7907-be96-e1734d3217a3" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_01a17d4e-8af5-77d3-b943-e80c92caa9d0" xlink:to="loc_srt_ProductOrServiceAxis_01a17d4e-8af5-7907-be96-e1734d3217a3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_01a17d4e-8af5-7907-be96-e1734d3217a3_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_01a17d4e-8af5-7907-be96-e1734d3217a3" xlink:to="loc_srt_ProductsAndServicesDomain_01a17d4e-8af5-7907-be96-e1734d3217a3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_01a17d4e-8af5-7f46-aeca-83acdb3a2df1" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_01a17d4e-8af5-7907-be96-e1734d3217a3" xlink:to="loc_srt_ProductsAndServicesDomain_01a17d4e-8af5-7f46-aeca-83acdb3a2df1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicenseMember_01a17d4e-8af5-72df-9b1e-bc8d0e58d85e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LicenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_01a17d4e-8af5-7f46-aeca-83acdb3a2df1" xlink:to="loc_us-gaap_LicenseMember_01a17d4e-8af5-72df-9b1e-bc8d0e58d85e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_01a17d4e-8af5-7028-b64b-0bc65fba3d5b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_01a17d4e-8af5-7898-8387-797dde94ca4b" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_01a17d4e-8af5-7028-b64b-0bc65fba3d5b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_CashCashEquivalentsRestrictedCashAndMarketableSecurities_019fceb7-6632-799d-bc64-c5d3018980f2" xlink:href="arvn-20260930.xsd#arvn_CashCashEquivalentsRestrictedCashAndMarketableSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_01a17d4e-8af5-7898-8387-797dde94ca4b" xlink:to="loc_arvn_CashCashEquivalentsRestrictedCashAndMarketableSecurities_019fceb7-6632-799d-bc64-c5d3018980f2" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.arvinas.com/role/ResearchCollaborationandLicenseAgreementsAdditionalInformationDetails" xlink:type="simple" xlink:href="arvn-20260930.xsd#ResearchCollaborationandLicenseAgreementsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.arvinas.com/role/ResearchCollaborationandLicenseAgreementsAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:href="arvn-20260930.xsd#arvn_ResearchCollaborationAndLicenseAgreementsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ResearchCollaborationAndLicenseAgreementsTable_019fceb7-6632-7234-9ee0-29bd404f4714" xlink:href="arvn-20260930.xsd#arvn_ResearchCollaborationAndLicenseAgreementsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_arvn_ResearchCollaborationAndLicenseAgreementsTable_019fceb7-6632-7234-9ee0-29bd404f4714" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019fceb7-6632-749c-9f39-3f31a63edea1" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsTable_019fceb7-6632-7234-9ee0-29bd404f4714" xlink:to="loc_srt_CounterpartyNameAxis_019fceb7-6632-749c-9f39-3f31a63edea1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-6632-749c-9f39-3f31a63edea1_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019fceb7-6632-749c-9f39-3f31a63edea1" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-6632-749c-9f39-3f31a63edea1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-6632-7e39-9148-6ebb7450e18b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019fceb7-6632-749c-9f39-3f31a63edea1" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-6632-7e39-9148-6ebb7450e18b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_RigelPharmaceuticalsInc.Member_019fceb7-6632-7739-a180-adb30e966159" xlink:href="arvn-20260930.xsd#arvn_RigelPharmaceuticalsInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-6632-7e39-9148-6ebb7450e18b" xlink:to="loc_arvn_RigelPharmaceuticalsInc.Member_019fceb7-6632-7739-a180-adb30e966159" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_PfizerInc.Member_019fceb7-6632-71ff-94e4-210ddb35837c" xlink:href="arvn-20260930.xsd#arvn_PfizerInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-6632-7e39-9148-6ebb7450e18b" xlink:to="loc_arvn_PfizerInc.Member_019fceb7-6632-71ff-94e4-210ddb35837c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_VepdegestrantMember_019fceb7-6632-7f10-836c-1030157729ea" xlink:href="arvn-20260930.xsd#arvn_VepdegestrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-6632-7e39-9148-6ebb7450e18b" xlink:to="loc_arvn_VepdegestrantMember_019fceb7-6632-7f10-836c-1030157729ea" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_NovartisPharmaAGMember_019fceb7-6632-7202-86b3-c5cb86b1fd92" xlink:href="arvn-20260930.xsd#arvn_NovartisPharmaAGMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-6632-7e39-9148-6ebb7450e18b" xlink:to="loc_arvn_NovartisPharmaAGMember_019fceb7-6632-7202-86b3-c5cb86b1fd92" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_GenentechIncorporationAndFHoffmanLaRocheLimitedMember_019fceb7-6632-7fcf-82b5-a6038d3b0674" xlink:href="arvn-20260930.xsd#arvn_GenentechIncorporationAndFHoffmanLaRocheLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-6632-7e39-9148-6ebb7450e18b" xlink:to="loc_arvn_GenentechIncorporationAndFHoffmanLaRocheLimitedMember_019fceb7-6632-7fcf-82b5-a6038d3b0674" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019fceb7-6632-7c5e-9672-104de34c88dd" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsTable_019fceb7-6632-7234-9ee0-29bd404f4714" xlink:to="loc_srt_ProductOrServiceAxis_019fceb7-6632-7c5e-9672-104de34c88dd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019fceb7-6632-7c5e-9672-104de34c88dd_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019fceb7-6632-7c5e-9672-104de34c88dd" xlink:to="loc_srt_ProductsAndServicesDomain_019fceb7-6632-7c5e-9672-104de34c88dd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019fceb7-6632-70c1-bc32-017a5d9b8f38" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019fceb7-6632-7c5e-9672-104de34c88dd" xlink:to="loc_srt_ProductsAndServicesDomain_019fceb7-6632-70c1-bc32-017a5d9b8f38" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicenseMember_019fceb7-6632-7326-94cb-8a3cd9afd741" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LicenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fceb7-6632-70c1-bc32-017a5d9b8f38" xlink:to="loc_us-gaap_LicenseMember_019fceb7-6632-7326-94cb-8a3cd9afd741" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_LicenseAgreementReimbursementFeesMember_019fceb7-6632-7ba2-a8c7-eeee63d1823c" xlink:href="arvn-20260930.xsd#arvn_LicenseAgreementReimbursementFeesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LicenseMember_019fceb7-6632-7326-94cb-8a3cd9afd741" xlink:to="loc_arvn_LicenseAgreementReimbursementFeesMember_019fceb7-6632-7ba2-a8c7-eeee63d1823c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_LicenseAgreementSalesBasedRoyaltiesMember_01a18347-9db1-7298-ab00-96dd24f444c7" xlink:href="arvn-20260930.xsd#arvn_LicenseAgreementSalesBasedRoyaltiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LicenseMember_019fceb7-6632-7326-94cb-8a3cd9afd741" xlink:to="loc_arvn_LicenseAgreementSalesBasedRoyaltiesMember_01a18347-9db1-7298-ab00-96dd24f444c7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_LicenseAgreementExcludingCostReimbursementFeesMember_01a18349-0cfd-7cb4-8bad-9e70d6d34dc6" xlink:href="arvn-20260930.xsd#arvn_LicenseAgreementExcludingCostReimbursementFeesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LicenseMember_019fceb7-6632-7326-94cb-8a3cd9afd741" xlink:to="loc_arvn_LicenseAgreementExcludingCostReimbursementFeesMember_01a18349-0cfd-7cb4-8bad-9e70d6d34dc6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_MilestoneRevenueMember_019fceb7-6632-70d6-8bbf-49fae49f8cd1" xlink:href="arvn-20260930.xsd#arvn_MilestoneRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fceb7-6632-70c1-bc32-017a5d9b8f38" xlink:to="loc_arvn_MilestoneRevenueMember_019fceb7-6632-70d6-8bbf-49fae49f8cd1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019fceb7-6632-7db9-bec2-54d6b2a59097" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsTable_019fceb7-6632-7234-9ee0-29bd404f4714" xlink:to="loc_srt_RangeAxis_019fceb7-6632-7db9-bec2-54d6b2a59097" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fceb7-6632-7db9-bec2-54d6b2a59097_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019fceb7-6632-7db9-bec2-54d6b2a59097" xlink:to="loc_srt_RangeMember_019fceb7-6632-7db9-bec2-54d6b2a59097_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fceb7-6632-7cb7-8ca0-ec6bb060ff97" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019fceb7-6632-7db9-bec2-54d6b2a59097" xlink:to="loc_srt_RangeMember_019fceb7-6632-7cb7-8ca0-ec6bb060ff97" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019fceb7-6632-74f6-8451-89a35d1c2b6e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019fceb7-6632-7cb7-8ca0-ec6bb060ff97" xlink:to="loc_srt_MaximumMember_019fceb7-6632-74f6-8451-89a35d1c2b6e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_019fceb7-6632-774b-8f73-799dc5152523" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsTable_019fceb7-6632-7234-9ee0-29bd404f4714" xlink:to="loc_us-gaap_TypeOfArrangementAxis_019fceb7-6632-774b-8f73-799dc5152523" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-6632-774b-8f73-799dc5152523_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_019fceb7-6632-774b-8f73-799dc5152523" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-6632-774b-8f73-799dc5152523_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-6632-756d-9be8-e82699aa9786" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_019fceb7-6632-774b-8f73-799dc5152523" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-6632-756d-9be8-e82699aa9786" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_CollaborationAgreementMember_019fceb7-6632-70b4-a0d8-14fb1ab3f9cb" xlink:href="arvn-20260930.xsd#arvn_CollaborationAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-6632-756d-9be8-e82699aa9786" xlink:to="loc_arvn_CollaborationAgreementMember_019fceb7-6632-70b4-a0d8-14fb1ab3f9cb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_RegulatoryAndSalesBasedMilestonesMember_019fceb7-6632-75b1-86e6-5f9ae71eaab0" xlink:href="arvn-20260930.xsd#arvn_RegulatoryAndSalesBasedMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-6632-756d-9be8-e82699aa9786" xlink:to="loc_arvn_RegulatoryAndSalesBasedMilestonesMember_019fceb7-6632-75b1-86e6-5f9ae71eaab0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_RegulatoryMilestonePaymentsMember_019fceb7-6632-785b-bed7-30fc82fcacc8" xlink:href="arvn-20260930.xsd#arvn_RegulatoryMilestonePaymentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-6632-756d-9be8-e82699aa9786" xlink:to="loc_arvn_RegulatoryMilestonePaymentsMember_019fceb7-6632-785b-bed7-30fc82fcacc8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_SalesBasedMilestonesMember_019fceb7-6632-74af-8903-deab43e795a9" xlink:href="arvn-20260930.xsd#arvn_SalesBasedMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-6632-756d-9be8-e82699aa9786" xlink:to="loc_arvn_SalesBasedMilestonesMember_019fceb7-6632-74af-8903-deab43e795a9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_OptionPaymentsToLicenseAgreementMember_019fceb7-6632-70dd-9f25-98f28999c06e" xlink:href="arvn-20260930.xsd#arvn_OptionPaymentsToLicenseAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-6632-756d-9be8-e82699aa9786" xlink:to="loc_arvn_OptionPaymentsToLicenseAgreementMember_019fceb7-6632-70dd-9f25-98f28999c06e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_DevelopmentMilestonePaymentsMember_019fceb7-6632-70d4-a583-313c6d5cac23" xlink:href="arvn-20260930.xsd#arvn_DevelopmentMilestonePaymentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-6632-756d-9be8-e82699aa9786" xlink:to="loc_arvn_DevelopmentMilestonePaymentsMember_019fceb7-6632-70d4-a583-313c6d5cac23" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_SalesBasedMilestonePaymentsMember_019fceb7-6632-7598-8506-f75aad55f04a" xlink:href="arvn-20260930.xsd#arvn_SalesBasedMilestonePaymentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-6632-756d-9be8-e82699aa9786" xlink:to="loc_arvn_SalesBasedMilestonePaymentsMember_019fceb7-6632-7598-8506-f75aad55f04a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_CommercialMilestonesMember_019fceb7-6632-7619-80e2-ce7340cef89b" xlink:href="arvn-20260930.xsd#arvn_CommercialMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-6632-756d-9be8-e82699aa9786" xlink:to="loc_arvn_CommercialMilestonesMember_019fceb7-6632-7619-80e2-ce7340cef89b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_PfizerCollaborationAgreementMember_019fceb7-6632-758b-ad1c-4e34665fe9b3" xlink:href="arvn-20260930.xsd#arvn_PfizerCollaborationAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-6632-756d-9be8-e82699aa9786" xlink:to="loc_arvn_PfizerCollaborationAgreementMember_019fceb7-6632-758b-ad1c-4e34665fe9b3" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_019fceb7-6632-76a9-8f8b-2db3fa46b2f5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ChangeInAccountingEstimateByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsTable_019fceb7-6632-7234-9ee0-29bd404f4714" xlink:to="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_019fceb7-6632-76a9-8f8b-2db3fa46b2f5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_019fceb7-6632-76a9-8f8b-2db3fa46b2f5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ChangeInAccountingEstimateTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_019fceb7-6632-76a9-8f8b-2db3fa46b2f5" xlink:to="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_019fceb7-6632-76a9-8f8b-2db3fa46b2f5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_019fceb7-6632-7ab0-8e6d-e5242146bcb2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ChangeInAccountingEstimateTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_019fceb7-6632-76a9-8f8b-2db3fa46b2f5" xlink:to="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_019fceb7-6632-7ab0-8e6d-e5242146bcb2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_RemovalOfCombinationTrialsMember_019fceb7-6632-768f-9b11-8f769222330d" xlink:href="arvn-20260930.xsd#arvn_RemovalOfCombinationTrialsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_019fceb7-6632-7ab0-8e6d-e5242146bcb2" xlink:to="loc_arvn_RemovalOfCombinationTrialsMember_019fceb7-6632-768f-9b11-8f769222330d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_UpdatedResearchTimelinesMember_019fceb7-6632-7d35-bcd4-725610d31223" xlink:href="arvn-20260930.xsd#arvn_UpdatedResearchTimelinesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_019fceb7-6632-7ab0-8e6d-e5242146bcb2" xlink:to="loc_arvn_UpdatedResearchTimelinesMember_019fceb7-6632-7d35-bcd4-725610d31223" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_RevenueFromContractWithCustomerDevelopmentActivityCostsMaximumReimbursement_019fceb7-6632-7468-bfdc-65429210fe13" xlink:href="arvn-20260930.xsd#arvn_RevenueFromContractWithCustomerDevelopmentActivityCostsMaximumReimbursement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_arvn_RevenueFromContractWithCustomerDevelopmentActivityCostsMaximumReimbursement_019fceb7-6632-7468-bfdc-65429210fe13" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_DevelopmentActivitiesAmountToRefundPercentage_019fceb7-6632-72b4-99a0-575c56f88185" xlink:href="arvn-20260930.xsd#arvn_DevelopmentActivitiesAmountToRefundPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_arvn_DevelopmentActivitiesAmountToRefundPercentage_019fceb7-6632-72b4-99a0-575c56f88185" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019fceb7-6632-7f9c-85d8-412ffc40f011" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019fceb7-6632-7f9c-85d8-412ffc40f011" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_RevenueFromContractWithCustomerAggregateUpfrontPayment_019fceb7-6632-7ea8-afb1-16a81023fc23" xlink:href="arvn-20260930.xsd#arvn_RevenueFromContractWithCustomerAggregateUpfrontPayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_arvn_RevenueFromContractWithCustomerAggregateUpfrontPayment_019fceb7-6632-7ea8-afb1-16a81023fc23" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetNet_019fceb7-6632-7c11-9b56-9a36027e5ed3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerAssetNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_us-gaap_ContractWithCustomerAssetNet_019fceb7-6632-7c11-9b56-9a36027e5ed3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_RevenueRemainingPerformanceObligationMaximumContingentPaymentsBasedOnMilestones_019fceb7-6632-73c9-ba90-62fee3f16fb6" xlink:href="arvn-20260930.xsd#arvn_RevenueRemainingPerformanceObligationMaximumContingentPaymentsBasedOnMilestones"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_arvn_RevenueRemainingPerformanceObligationMaximumContingentPaymentsBasedOnMilestones_019fceb7-6632-73c9-ba90-62fee3f16fb6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ConsiderationPayableUnderCollaborationAgreement_019fceb7-6632-7c53-80e5-56fc6489cd8d" xlink:href="arvn-20260930.xsd#arvn_ConsiderationPayableUnderCollaborationAgreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_arvn_ConsiderationPayableUnderCollaborationAgreement_019fceb7-6632-7c53-80e5-56fc6489cd8d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_DirectAndIncrementalCostsIncurredToObtainTheContract_019fceb7-6632-71f1-ab6a-aacd55d9352f" xlink:href="arvn-20260930.xsd#arvn_DirectAndIncrementalCostsIncurredToObtainTheContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_arvn_DirectAndIncrementalCostsIncurredToObtainTheContract_019fceb7-6632-71f1-ab6a-aacd55d9352f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_CollaborationContractAssetAndOtherAssets_019fceb7-6632-7a6d-851c-27b0cf3ff422" xlink:href="arvn-20260930.xsd#arvn_CollaborationContractAssetAndOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_arvn_CollaborationContractAssetAndOtherAssets_019fceb7-6632-7a6d-851c-27b0cf3ff422" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_019fceb7-6632-7614-a8d6-92c5b41bdb1d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_019fceb7-6632-7614-a8d6-92c5b41bdb1d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_019fceb7-66c4-7a2a-96bf-85812752332d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_019fceb7-66c4-7a2a-96bf-85812752332d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_CollaborationLiability_019fceb7-66c4-7136-b049-5ae22ff7ba99" xlink:href="arvn-20260930.xsd#arvn_CollaborationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_arvn_CollaborationLiability_019fceb7-66c4-7136-b049-5ae22ff7ba99" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromCollaborators_019fceb7-66c4-7461-a4fe-1c8c4836e87a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromCollaborators"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_us-gaap_ProceedsFromCollaborators_019fceb7-66c4-7461-a4fe-1c8c4836e87a" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_019fceb7-66c4-7db9-b2f8-dbb2131bb1d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_us-gaap_ContractWithCustomerLiability_019fceb7-66c4-7db9-b2f8-dbb2131bb1d6" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_RevenueRemainingPerformanceObligationContingentPayments_019fceb7-66c4-7783-90f4-59ffa53f1f50" xlink:href="arvn-20260930.xsd#arvn_RevenueRemainingPerformanceObligationContingentPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_arvn_RevenueRemainingPerformanceObligationContingentPayments_019fceb7-66c4-7783-90f4-59ffa53f1f50" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_019fceb7-66c4-7aec-a625-8a47987d25e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_us-gaap_OperatingExpenses_019fceb7-66c4-7aec-a625-8a47987d25e5" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019fceb7-66c4-77cb-bbfc-6f013d4b540d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_us-gaap_NetIncomeLoss_019fceb7-66c4-77cb-bbfc-6f013d4b540d" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_019fceb7-66c4-7e28-aa72-1da6c5bee5f4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_us-gaap_EarningsPerShareBasic_019fceb7-66c4-7e28-aa72-1da6c5bee5f4" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019fceb7-66c4-77f2-b159-8068d3edc278" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-6632-7a84-87dc-6c297b9185c8" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019fceb7-66c4-77f2-b159-8068d3edc278" xlink:type="arc" order="18"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.arvinas.com/role/ResearchCollaborationandLicenseAgreementsScheduleofSourcesofRevenueDetails" xlink:type="simple" xlink:href="arvn-20260930.xsd#ResearchCollaborationandLicenseAgreementsScheduleofSourcesofRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.arvinas.com/role/ResearchCollaborationandLicenseAgreementsScheduleofSourcesofRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-66c4-73f0-aa0c-b98c29ed6c49" xlink:href="arvn-20260930.xsd#arvn_ResearchCollaborationAndLicenseAgreementsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ResearchCollaborationAndLicenseAgreementsTable_019fceb7-66c4-7dc3-adab-7cad4781c676" xlink:href="arvn-20260930.xsd#arvn_ResearchCollaborationAndLicenseAgreementsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-66c4-73f0-aa0c-b98c29ed6c49" xlink:to="loc_arvn_ResearchCollaborationAndLicenseAgreementsTable_019fceb7-66c4-7dc3-adab-7cad4781c676" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019fceb7-66c4-7fe5-a734-1f0bfae2369c" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsTable_019fceb7-66c4-7dc3-adab-7cad4781c676" xlink:to="loc_srt_CounterpartyNameAxis_019fceb7-66c4-7fe5-a734-1f0bfae2369c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-66c4-7fe5-a734-1f0bfae2369c_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019fceb7-66c4-7fe5-a734-1f0bfae2369c" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-66c4-7fe5-a734-1f0bfae2369c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-66c4-7c5d-8683-1b83466c75a0" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019fceb7-66c4-7fe5-a734-1f0bfae2369c" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-66c4-7c5d-8683-1b83466c75a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_VepdegestrantMember_019fceb7-66c4-782b-bc28-ebe5ae332062" xlink:href="arvn-20260930.xsd#arvn_VepdegestrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-66c4-7c5d-8683-1b83466c75a0" xlink:to="loc_arvn_VepdegestrantMember_019fceb7-66c4-782b-bc28-ebe5ae332062" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_PfizerInc.Member_019fceb7-66c4-7e7b-916a-c2c46303c9b9" xlink:href="arvn-20260930.xsd#arvn_PfizerInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-66c4-7c5d-8683-1b83466c75a0" xlink:to="loc_arvn_PfizerInc.Member_019fceb7-66c4-7e7b-916a-c2c46303c9b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_NovartisPharmaAGMember_01a15539-8b18-7c21-b41d-7bae50c80f0f" xlink:href="arvn-20260930.xsd#arvn_NovartisPharmaAGMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-66c4-7c5d-8683-1b83466c75a0" xlink:to="loc_arvn_NovartisPharmaAGMember_01a15539-8b18-7c21-b41d-7bae50c80f0f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_RigelPharmaceuticalsInc.Member_019fceb7-66c4-7f81-9580-4ce5b20204ea" xlink:href="arvn-20260930.xsd#arvn_RigelPharmaceuticalsInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-66c4-7c5d-8683-1b83466c75a0" xlink:to="loc_arvn_RigelPharmaceuticalsInc.Member_019fceb7-66c4-7f81-9580-4ce5b20204ea" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019fceb7-66c4-77a9-a3b6-f851617ea06b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsTable_019fceb7-66c4-7dc3-adab-7cad4781c676" xlink:to="loc_srt_ProductOrServiceAxis_019fceb7-66c4-77a9-a3b6-f851617ea06b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019fceb7-66c4-77a9-a3b6-f851617ea06b_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019fceb7-66c4-77a9-a3b6-f851617ea06b" xlink:to="loc_srt_ProductsAndServicesDomain_019fceb7-66c4-77a9-a3b6-f851617ea06b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019fceb7-66c4-7422-b349-ac8b83e51dde" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019fceb7-66c4-77a9-a3b6-f851617ea06b" xlink:to="loc_srt_ProductsAndServicesDomain_019fceb7-66c4-7422-b349-ac8b83e51dde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_CollaborationAgreementRevenueMember_019fceb7-66c4-77e9-bdb1-b3c565f47dec" xlink:href="arvn-20260930.xsd#arvn_CollaborationAgreementRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fceb7-66c4-7422-b349-ac8b83e51dde" xlink:to="loc_arvn_CollaborationAgreementRevenueMember_019fceb7-66c4-77e9-bdb1-b3c565f47dec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_MilestoneRevenueMember_019fceb7-66c4-7c56-bcfd-759ab2467f6b" xlink:href="arvn-20260930.xsd#arvn_MilestoneRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fceb7-66c4-7422-b349-ac8b83e51dde" xlink:to="loc_arvn_MilestoneRevenueMember_019fceb7-66c4-7c56-bcfd-759ab2467f6b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicenseMember_019fceb7-66c4-7d79-a89f-58cd8ec06f41" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LicenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fceb7-66c4-7422-b349-ac8b83e51dde" xlink:to="loc_us-gaap_LicenseMember_019fceb7-66c4-7d79-a89f-58cd8ec06f41" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019fceb7-66c4-72b6-a8ab-65491396c564" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_ResearchCollaborationAndLicenseAgreementsLineItems_019fceb7-66c4-73f0-aa0c-b98c29ed6c49" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019fceb7-66c4-72b6-a8ab-65491396c564" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.arvinas.com/role/MarketableSecuritiesandFairValueMeasurementsDetails" xlink:type="simple" xlink:href="arvn-20260930.xsd#MarketableSecuritiesandFairValueMeasurementsDetails"/>
  <link:definitionLink xlink:role="http://www.arvinas.com/role/MarketableSecuritiesandFairValueMeasurementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fceb7-66c4-7eb5-b6fc-b061035baf37" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fceb7-66c4-783b-966d-4ae8cd4bf6f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fceb7-66c4-7eb5-b6fc-b061035baf37" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fceb7-66c4-783b-966d-4ae8cd4bf6f1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019fceb7-66c4-7cb0-90c1-477c28c3fe26" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fceb7-66c4-783b-966d-4ae8cd4bf6f1" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019fceb7-66c4-7cb0-90c1-477c28c3fe26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fceb7-66c4-7cb0-90c1-477c28c3fe26_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019fceb7-66c4-7cb0-90c1-477c28c3fe26" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fceb7-66c4-7cb0-90c1-477c28c3fe26_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fceb7-66c4-7199-9760-ff805342e4ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019fceb7-66c4-7cb0-90c1-477c28c3fe26" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fceb7-66c4-7199-9760-ff805342e4ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019fceb7-66c4-7b1b-a0b9-2d90ba465000" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019fceb7-66c4-7199-9760-ff805342e4ee" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019fceb7-66c4-7b1b-a0b9-2d90ba465000" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019fceb7-66c4-7781-8e89-a9f690238dff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019fceb7-66c4-783b-966d-4ae8cd4bf6f1" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019fceb7-66c4-7781-8e89-a9f690238dff" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fceb7-66c4-7781-8e89-a9f690238dff_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019fceb7-66c4-7781-8e89-a9f690238dff" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fceb7-66c4-7781-8e89-a9f690238dff_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fceb7-66c4-72b7-b212-3fc6ca41510d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019fceb7-66c4-7781-8e89-a9f690238dff" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fceb7-66c4-72b7-b212-3fc6ca41510d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateBondSecuritiesMember_019fceb7-66c4-7861-8d55-a51561cb9b47" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateBondSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fceb7-66c4-72b7-b212-3fc6ca41510d" xlink:to="loc_us-gaap_CorporateBondSecuritiesMember_019fceb7-66c4-7861-8d55-a51561cb9b47" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentDebtSecuritiesMember_019fceb7-66c4-71ae-a9cb-5cf65f0a95e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_USGovernmentDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019fceb7-66c4-72b7-b212-3fc6ca41510d" xlink:to="loc_us-gaap_USGovernmentDebtSecuritiesMember_019fceb7-66c4-71ae-a9cb-5cf65f0a95e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019fceb7-66c4-71b3-97cd-dcc15143e288" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fceb7-66c4-7eb5-b6fc-b061035baf37" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019fceb7-66c4-71b3-97cd-dcc15143e288" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_019fceb7-66c4-71fe-b709-c1cecd5d7382" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fceb7-66c4-7eb5-b6fc-b061035baf37" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_019fceb7-66c4-71fe-b709-c1cecd5d7382" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_019fceb7-66c4-732a-84d3-333045c32fd8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fceb7-66c4-7eb5-b6fc-b061035baf37" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_019fceb7-66c4-732a-84d3-333045c32fd8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019fceb7-66c4-71ff-aca2-577c4a8d5d7f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019fceb7-66c4-7eb5-b6fc-b061035baf37" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019fceb7-66c4-71ff-aca2-577c4a8d5d7f" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.arvinas.com/role/PropertyEquipmentandLeaseholdImprovementsScheduleofPropertyEquipmentandLeaseholdImprovementsDetails" xlink:type="simple" xlink:href="arvn-20260930.xsd#PropertyEquipmentandLeaseholdImprovementsScheduleofPropertyEquipmentandLeaseholdImprovementsDetails"/>
  <link:definitionLink xlink:role="http://www.arvinas.com/role/PropertyEquipmentandLeaseholdImprovementsScheduleofPropertyEquipmentandLeaseholdImprovementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fceb7-66c4-7f86-afc3-d03dae397ff7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019fceb7-66c4-7e5a-8a3c-593a7dfa3cb8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fceb7-66c4-7f86-afc3-d03dae397ff7" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019fceb7-66c4-7e5a-8a3c-593a7dfa3cb8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019fceb7-66c4-7241-a4e8-f122a331e22d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019fceb7-66c4-7e5a-8a3c-593a7dfa3cb8" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019fceb7-66c4-7241-a4e8-f122a331e22d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019fceb7-66c4-7241-a4e8-f122a331e22d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019fceb7-66c4-7241-a4e8-f122a331e22d" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019fceb7-66c4-7241-a4e8-f122a331e22d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019fceb7-66c4-7067-906e-66a4e01e12fd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019fceb7-66c4-7241-a4e8-f122a331e22d" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019fceb7-66c4-7067-906e-66a4e01e12fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_LaboratoryEquipmentMember_019fceb7-66c4-7852-bd79-a9aac4342aff" xlink:href="arvn-20260930.xsd#arvn_LaboratoryEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019fceb7-66c4-7067-906e-66a4e01e12fd" xlink:to="loc_arvn_LaboratoryEquipmentMember_019fceb7-66c4-7852-bd79-a9aac4342aff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_019fceb7-66c4-736f-918c-23ab2b859f29" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019fceb7-66c4-7067-906e-66a4e01e12fd" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_019fceb7-66c4-736f-918c-23ab2b859f29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OfficeEquipmentMember_019fceb7-66c4-7956-b429-c17932730692" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OfficeEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019fceb7-66c4-7067-906e-66a4e01e12fd" xlink:to="loc_us-gaap_OfficeEquipmentMember_019fceb7-66c4-7956-b429-c17932730692" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_019fceb7-66c4-7b78-9c00-9fb93bb2bc0c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fceb7-66c4-7f86-afc3-d03dae397ff7" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_019fceb7-66c4-7b78-9c00-9fb93bb2bc0c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019fceb7-66c4-7257-ac03-165d79b61865" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fceb7-66c4-7f86-afc3-d03dae397ff7" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019fceb7-66c4-7257-ac03-165d79b61865" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019fceb7-66c4-7fb6-b715-c4d1df883c59" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019fceb7-66c4-7f86-afc3-d03dae397ff7" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019fceb7-66c4-7fb6-b715-c4d1df883c59" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.arvinas.com/role/RightofUseAssetsandLiabilitiesAdditionalInformationDetails" xlink:type="simple" xlink:href="arvn-20260930.xsd#RightofUseAssetsandLiabilitiesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.arvinas.com/role/RightofUseAssetsandLiabilitiesAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_019fceb7-66c4-719b-8a3a-e9d6db2ae7b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_019fceb7-66c4-7ebf-a8eb-7a215a3cc975" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019fceb7-66c4-719b-8a3a-e9d6db2ae7b0" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_019fceb7-66c4-7ebf-a8eb-7a215a3cc975" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019fceb7-66c4-7642-9f7f-955302309498" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_019fceb7-66c4-7ebf-a8eb-7a215a3cc975" xlink:to="loc_srt_RangeAxis_019fceb7-66c4-7642-9f7f-955302309498" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fceb7-66c4-7642-9f7f-955302309498_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019fceb7-66c4-7642-9f7f-955302309498" xlink:to="loc_srt_RangeMember_019fceb7-66c4-7642-9f7f-955302309498_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fceb7-66c4-723a-b525-290ad27e30c6" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019fceb7-66c4-7642-9f7f-955302309498" xlink:to="loc_srt_RangeMember_019fceb7-66c4-723a-b525-290ad27e30c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019fceb7-66c4-72a8-9690-d8cb083cb20e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019fceb7-66c4-723a-b525-290ad27e30c6" xlink:to="loc_srt_MinimumMember_019fceb7-66c4-72a8-9690-d8cb083cb20e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_PercentageOfIncrementalBorrowingForLeasePayments_019fceb7-66c4-71db-86a6-47d87f18fa89" xlink:href="arvn-20260930.xsd#arvn_PercentageOfIncrementalBorrowingForLeasePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019fceb7-66c4-719b-8a3a-e9d6db2ae7b0" xlink:to="loc_arvn_PercentageOfIncrementalBorrowingForLeasePayments_019fceb7-66c4-71db-86a6-47d87f18fa89" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_019fceb7-66c4-7abf-a690-7f88d1c1c223" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019fceb7-66c4-719b-8a3a-e9d6db2ae7b0" xlink:to="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_019fceb7-66c4-7abf-a690-7f88d1c1c223" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.arvinas.com/role/LongTermDebtAdditionalInformationDetails" xlink:type="simple" xlink:href="arvn-20260930.xsd#LongTermDebtAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.arvinas.com/role/LongTermDebtAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019fceb7-66c5-7884-9606-ee642862503f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019fceb7-66c5-7be5-a22e-13f39408c811" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fceb7-66c5-7884-9606-ee642862503f" xlink:to="loc_us-gaap_DebtInstrumentTable_019fceb7-66c5-7be5-a22e-13f39408c811" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019fceb7-66c5-73d4-a8e5-e1be324c8783" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019fceb7-66c5-7be5-a22e-13f39408c811" xlink:to="loc_us-gaap_DebtInstrumentAxis_019fceb7-66c5-73d4-a8e5-e1be324c8783" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019fceb7-66c5-73d4-a8e5-e1be324c8783_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019fceb7-66c5-73d4-a8e5-e1be324c8783" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019fceb7-66c5-73d4-a8e5-e1be324c8783_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019fceb7-66c5-7b80-a3e8-bc381b65b8b7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019fceb7-66c5-73d4-a8e5-e1be324c8783" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019fceb7-66c5-7b80-a3e8-bc381b65b8b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_TwoThousandAndEighteenAssistanceAgreementMember_019fceb7-66c5-7f33-85d1-0e67dec8b50d" xlink:href="arvn-20260930.xsd#arvn_TwoThousandAndEighteenAssistanceAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019fceb7-66c5-7b80-a3e8-bc381b65b8b7" xlink:to="loc_arvn_TwoThousandAndEighteenAssistanceAgreementMember_019fceb7-66c5-7f33-85d1-0e67dec8b50d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019fceb7-66c5-7834-9390-50f4f7d768ac" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019fceb7-66c5-7be5-a22e-13f39408c811" xlink:to="loc_srt_StatementGeographicalAxis_019fceb7-66c5-7834-9390-50f4f7d768ac" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019fceb7-66c5-7834-9390-50f4f7d768ac_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019fceb7-66c5-7834-9390-50f4f7d768ac" xlink:to="loc_srt_SegmentGeographicalDomain_019fceb7-66c5-7834-9390-50f4f7d768ac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019fceb7-66c5-7f5d-b4b5-ada7f70fec5e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019fceb7-66c5-7834-9390-50f4f7d768ac" xlink:to="loc_srt_SegmentGeographicalDomain_019fceb7-66c5-7f5d-b4b5-ada7f70fec5e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_CT_019fceb7-66c5-7770-8dcc-394394bdb7fc" xlink:href="https://xbrl.sec.gov/stpr/2026/stpr-2026.xsd#stpr_CT"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019fceb7-66c5-7f5d-b4b5-ada7f70fec5e" xlink:to="loc_stpr_CT_019fceb7-66c5-7770-8dcc-394394bdb7fc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019fceb7-66c5-790f-9a09-9ad4d642a8b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fceb7-66c5-7884-9606-ee642862503f" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019fceb7-66c5-790f-9a09-9ad4d642a8b8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_DebtInstrumentLoanForgiveness_019fceb7-66c5-7831-928a-2fc5044d696b" xlink:href="arvn-20260930.xsd#arvn_DebtInstrumentLoanForgiveness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fceb7-66c5-7884-9606-ee642862503f" xlink:to="loc_arvn_DebtInstrumentLoanForgiveness_019fceb7-66c5-7831-928a-2fc5044d696b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019fceb7-66c5-7a16-8c6f-1efbc79ab753" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fceb7-66c5-7884-9606-ee642862503f" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019fceb7-66c5-7a16-8c6f-1efbc79ab753" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_DebtInstrumentInterestPaymentsTerm_019fceb7-66c5-7d63-936b-42a53ebd5d54" xlink:href="arvn-20260930.xsd#arvn_DebtInstrumentInterestPaymentsTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fceb7-66c5-7884-9606-ee642862503f" xlink:to="loc_arvn_DebtInstrumentInterestPaymentsTerm_019fceb7-66c5-7d63-936b-42a53ebd5d54" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_PercentageOfLiquidatedDamages_019fceb7-66c5-798f-acdf-9644e3fbc6dc" xlink:href="arvn-20260930.xsd#arvn_PercentageOfLiquidatedDamages"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fceb7-66c5-7884-9606-ee642862503f" xlink:to="loc_arvn_PercentageOfLiquidatedDamages_019fceb7-66c5-798f-acdf-9644e3fbc6dc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDebt_019fceb7-66c5-784f-8e9f-7584a429ace8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019fceb7-66c5-7884-9606-ee642862503f" xlink:to="loc_us-gaap_InterestExpenseDebt_019fceb7-66c5-784f-8e9f-7584a429ace8" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.arvinas.com/role/EquityAdditionalInformationDetails" xlink:type="simple" xlink:href="arvn-20260930.xsd#EquityAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.arvinas.com/role/EquityAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-73e0-9e7d-9b9ec4883dff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-73e0-9e7d-9b9ec4883dff" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019fceb7-66c5-78bf-a94d-70de46dc831b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-73e0-9e7d-9b9ec4883dff" xlink:to="loc_srt_CounterpartyNameAxis_019fceb7-66c5-78bf-a94d-70de46dc831b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-66c5-78bf-a94d-70de46dc831b_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019fceb7-66c5-78bf-a94d-70de46dc831b" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-66c5-78bf-a94d-70de46dc831b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-66c5-7c7c-88cb-0843bbe6f616" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019fceb7-66c5-78bf-a94d-70de46dc831b" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-66c5-7c7c-88cb-0843bbe6f616" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_PiperSandlerAndCantorMember_019fceb7-66c5-7277-aedb-0b10a25e0138" xlink:href="arvn-20260930.xsd#arvn_PiperSandlerAndCantorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-66c5-7c7c-88cb-0843bbe6f616" xlink:to="loc_arvn_PiperSandlerAndCantorMember_019fceb7-66c5-7277-aedb-0b10a25e0138" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_019fceb7-66c5-7cee-8628-27a44349e767" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-73e0-9e7d-9b9ec4883dff" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_019fceb7-66c5-7cee-8628-27a44349e767" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019fceb7-66c5-7cee-8628-27a44349e767_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_019fceb7-66c5-7cee-8628-27a44349e767" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019fceb7-66c5-7cee-8628-27a44349e767_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019fceb7-66c5-7890-ba05-a5d91f2fbbb4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_019fceb7-66c5-7cee-8628-27a44349e767" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019fceb7-66c5-7890-ba05-a5d91f2fbbb4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_AtTheMarketOfferingMember_019fceb7-66c5-71b8-9597-360466b669c9" xlink:href="arvn-20260930.xsd#arvn_AtTheMarketOfferingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019fceb7-66c5-7890-ba05-a5d91f2fbbb4" xlink:to="loc_arvn_AtTheMarketOfferingMember_019fceb7-66c5-71b8-9597-360466b669c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_019fceb7-66c5-735c-8170-7968caaa45b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-73e0-9e7d-9b9ec4883dff" xlink:to="loc_us-gaap_TypeOfArrangementAxis_019fceb7-66c5-735c-8170-7968caaa45b6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-66c5-735c-8170-7968caaa45b6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_019fceb7-66c5-735c-8170-7968caaa45b6" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-66c5-735c-8170-7968caaa45b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-66c5-75f8-af7a-4127c54a2e48" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_019fceb7-66c5-735c-8170-7968caaa45b6" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-66c5-75f8-af7a-4127c54a2e48" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_EquityDistributionAgreementMember_019fceb7-66c5-7c9c-9561-1a009150a47b" xlink:href="arvn-20260930.xsd#arvn_EquityDistributionAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-66c5-75f8-af7a-4127c54a2e48" xlink:to="loc_arvn_EquityDistributionAgreementMember_019fceb7-66c5-7c9c-9561-1a009150a47b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019fceb7-66c5-74dc-97f9-c04b5407516a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-73e0-9e7d-9b9ec4883dff" xlink:to="loc_us-gaap_AwardTypeAxis_019fceb7-66c5-74dc-97f9-c04b5407516a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fceb7-66c5-74dc-97f9-c04b5407516a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019fceb7-66c5-74dc-97f9-c04b5407516a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fceb7-66c5-74dc-97f9-c04b5407516a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fceb7-66c5-7739-b6db-853763295130" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019fceb7-66c5-74dc-97f9-c04b5407516a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fceb7-66c5-7739-b6db-853763295130" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_019fceb7-66c5-75a5-a5f4-70b15fa9b137" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fceb7-66c5-7739-b6db-853763295130" xlink:to="loc_us-gaap_EmployeeStockMember_019fceb7-66c5-75a5-a5f4-70b15fa9b137" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019fceb7-66c5-73b8-9bec-fa20d40ce384" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fceb7-66c5-7739-b6db-853763295130" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019fceb7-66c5-73b8-9bec-fa20d40ce384" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019fceb7-66c5-7950-9d35-068a6e6189af" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-73e0-9e7d-9b9ec4883dff" xlink:to="loc_us-gaap_PlanNameAxis_019fceb7-66c5-7950-9d35-068a6e6189af" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019fceb7-66c5-7950-9d35-068a6e6189af_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019fceb7-66c5-7950-9d35-068a6e6189af" xlink:to="loc_us-gaap_PlanNameDomain_019fceb7-66c5-7950-9d35-068a6e6189af_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019fceb7-66c5-7913-a943-21b14d0064cc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019fceb7-66c5-7950-9d35-068a6e6189af" xlink:to="loc_us-gaap_PlanNameDomain_019fceb7-66c5-7913-a943-21b14d0064cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_TwoThousandEighteenStockIncentivePlanMember_019fceb7-66c5-7023-9388-c64922301ac9" xlink:href="arvn-20260930.xsd#arvn_TwoThousandEighteenStockIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019fceb7-66c5-7913-a943-21b14d0064cc" xlink:to="loc_arvn_TwoThousandEighteenStockIncentivePlanMember_019fceb7-66c5-7023-9388-c64922301ac9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019fceb7-66c5-739a-aa7f-f92be1fefaa0" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-73e0-9e7d-9b9ec4883dff" xlink:to="loc_srt_RangeAxis_019fceb7-66c5-739a-aa7f-f92be1fefaa0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fceb7-66c5-739a-aa7f-f92be1fefaa0_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019fceb7-66c5-739a-aa7f-f92be1fefaa0" xlink:to="loc_srt_RangeMember_019fceb7-66c5-739a-aa7f-f92be1fefaa0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fceb7-66c5-78df-8cb6-0e4e32c357c1" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019fceb7-66c5-739a-aa7f-f92be1fefaa0" xlink:to="loc_srt_RangeMember_019fceb7-66c5-78df-8cb6-0e4e32c357c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019fceb7-66c5-7d2b-89e7-025f403d8c2f" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019fceb7-66c5-78df-8cb6-0e4e32c357c1" xlink:to="loc_srt_MaximumMember_019fceb7-66c5-7d2b-89e7-025f403d8c2f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019fceb7-66c5-7af3-b07e-852da605e472" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019fceb7-66c5-78df-8cb6-0e4e32c357c1" xlink:to="loc_srt_MinimumMember_019fceb7-66c5-7af3-b07e-852da605e472" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_WeightedAverageMember_019fceb7-66c5-7ec5-b821-3b47fee6e000" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_WeightedAverageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019fceb7-66c5-78df-8cb6-0e4e32c357c1" xlink:to="loc_srt_WeightedAverageMember_019fceb7-66c5-7ec5-b821-3b47fee6e000" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_MaximumAggregateOfferingPriceOfCommonStock_019fceb7-66c5-7270-a17c-52ceca3a4868" xlink:href="arvn-20260930.xsd#arvn_MaximumAggregateOfferingPriceOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_arvn_MaximumAggregateOfferingPriceOfCommonStock_019fceb7-66c5-7270-a17c-52ceca3a4868" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_019fceb7-66c5-7d93-a3fe-77ce4b1b890c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_019fceb7-66c5-7d93-a3fe-77ce4b1b890c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_019fceb7-66c5-7f2a-ab2e-cdf3512ed75e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_019fceb7-66c5-7f2a-ab2e-cdf3512ed75e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_IncreaseInCapitalSharesReservedForFutureIssuanceRepresentedAsPercentageOnOutstandingCommonStock_019fceb7-66c5-7391-859c-6f74905e44c6" xlink:href="arvn-20260930.xsd#arvn_IncreaseInCapitalSharesReservedForFutureIssuanceRepresentedAsPercentageOnOutstandingCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_arvn_IncreaseInCapitalSharesReservedForFutureIssuanceRepresentedAsPercentageOnOutstandingCommonStock_019fceb7-66c5-7391-859c-6f74905e44c6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_019fceb7-66c5-74ed-a14e-301aa3ff11e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_019fceb7-66c5-74ed-a14e-301aa3ff11e0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_019fceb7-66c5-74c5-b218-3b132e04ab6c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_019fceb7-66c5-74c5-b218-3b132e04ab6c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOtherIncreasesDecreasesInPeriod_019fceb7-66c5-7400-bd2e-2ec985b1b5cd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOtherIncreasesDecreasesInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOtherIncreasesDecreasesInPeriod_019fceb7-66c5-7400-bd2e-2ec985b1b5cd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_019fceb7-66c5-74f8-a2f7-f79bf92b83d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_019fceb7-66c5-74f8-a2f7-f79bf92b83d5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019fceb7-66c5-7836-a849-b5f0d65921ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019fceb7-66c5-7836-a849-b5f0d65921ee" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ShareBasedPaymentArrangementExpenseDecreaseRelatedToModifications_019fceb7-66c5-73d3-aee3-50598d28d698" xlink:href="arvn-20260930.xsd#arvn_ShareBasedPaymentArrangementExpenseDecreaseRelatedToModifications"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_arvn_ShareBasedPaymentArrangementExpenseDecreaseRelatedToModifications_019fceb7-66c5-73d3-aee3-50598d28d698" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019fceb7-66c5-7ede-8b64-36e9a83170e1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019fceb7-66c5-7ede-8b64-36e9a83170e1" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019fceb7-66c5-7fd7-a569-de75b0325fbd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019fceb7-66c5-7fd7-a569-de75b0325fbd" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ShareBasedCompensationArrangementByShareBasedPaymentAwardInducementGrants_019fceb7-66c5-756c-bb6c-7c0ac9d77216" xlink:href="arvn-20260930.xsd#arvn_ShareBasedCompensationArrangementByShareBasedPaymentAwardInducementGrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_arvn_ShareBasedCompensationArrangementByShareBasedPaymentAwardInducementGrants_019fceb7-66c5-756c-bb6c-7c0ac9d77216" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019fceb7-66c5-7336-a76d-df0897f1c287" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019fceb7-66c5-7336-a76d-df0897f1c287" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_019fceb7-66c5-741c-8c9c-81cac7f5f0c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_019fceb7-66c5-741c-8c9c-81cac7f5f0c9" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsInducementGrants_019fceb7-66c5-7ae8-a17d-87c2e55a5df1" xlink:href="arvn-20260930.xsd#arvn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsInducementGrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_arvn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsInducementGrants_019fceb7-66c5-7ae8-a17d-87c2e55a5df1" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019fceb7-66c5-7f71-958c-8321dbd1369b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019fceb7-66c5-7f71-958c-8321dbd1369b" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueReleasedInPeriod_019fceb7-66c5-7007-bebb-afc5f51ebe5e" xlink:href="arvn-20260930.xsd#arvn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueReleasedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_arvn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueReleasedInPeriod_019fceb7-66c5-7007-bebb-afc5f51ebe5e" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_019fceb7-66c5-773f-90e0-e7cb8049b771" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7b9f-96f3-30e71ad572b6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_019fceb7-66c5-773f-90e0-e7cb8049b771" xlink:type="arc" order="18"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.arvinas.com/role/EquityScheduleofAssumptionsUsedtoDetermineFairValueofandStockOptionsGrantedDetails" xlink:type="simple" xlink:href="arvn-20260930.xsd#EquityScheduleofAssumptionsUsedtoDetermineFairValueofandStockOptionsGrantedDetails"/>
  <link:definitionLink xlink:role="http://www.arvinas.com/role/EquityScheduleofAssumptionsUsedtoDetermineFairValueofandStockOptionsGrantedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7798-a378-d37cbced0b78" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-760b-bd40-75c09d067a25" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7798-a378-d37cbced0b78" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-760b-bd40-75c09d067a25" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019fceb7-66c5-7e45-b1c4-d82dd2f00822" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-760b-bd40-75c09d067a25" xlink:to="loc_us-gaap_AwardTypeAxis_019fceb7-66c5-7e45-b1c4-d82dd2f00822" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fceb7-66c5-7e45-b1c4-d82dd2f00822_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019fceb7-66c5-7e45-b1c4-d82dd2f00822" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fceb7-66c5-7e45-b1c4-d82dd2f00822_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fceb7-66c5-79ac-81c3-48a14ab6dcfa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019fceb7-66c5-7e45-b1c4-d82dd2f00822" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fceb7-66c5-79ac-81c3-48a14ab6dcfa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019fceb7-66c5-7fa3-a045-adceb01f0965" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fceb7-66c5-79ac-81c3-48a14ab6dcfa" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019fceb7-66c5-7fa3-a045-adceb01f0965" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019fceb7-66c5-7819-9c72-a4a5a1e10ceb" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-760b-bd40-75c09d067a25" xlink:to="loc_srt_RangeAxis_019fceb7-66c5-7819-9c72-a4a5a1e10ceb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fceb7-66c5-7819-9c72-a4a5a1e10ceb_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019fceb7-66c5-7819-9c72-a4a5a1e10ceb" xlink:to="loc_srt_RangeMember_019fceb7-66c5-7819-9c72-a4a5a1e10ceb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fceb7-66c5-7a96-8a95-859319fbaf34" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019fceb7-66c5-7819-9c72-a4a5a1e10ceb" xlink:to="loc_srt_RangeMember_019fceb7-66c5-7a96-8a95-859319fbaf34" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019fceb7-66c5-7e72-89e9-cbb834eb9700" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019fceb7-66c5-7a96-8a95-859319fbaf34" xlink:to="loc_srt_MinimumMember_019fceb7-66c5-7e72-89e9-cbb834eb9700" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019fceb7-66c5-7538-93ad-6c449efcf749" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019fceb7-66c5-7a96-8a95-859319fbaf34" xlink:to="loc_srt_MaximumMember_019fceb7-66c5-7538-93ad-6c449efcf749" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_019fceb7-66c5-75e8-ac3d-0358822d268c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7798-a378-d37cbced0b78" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_019fceb7-66c5-75e8-ac3d-0358822d268c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_019fceb7-66c5-75ab-a4e7-5f13ff487656" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7798-a378-d37cbced0b78" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_019fceb7-66c5-75ab-a4e7-5f13ff487656" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019fceb7-66c5-7959-affe-d90decc69aad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7798-a378-d37cbced0b78" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019fceb7-66c5-7959-affe-d90decc69aad" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_019fceb7-66c5-7632-860e-6fffa149a1f3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7798-a378-d37cbced0b78" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_019fceb7-66c5-7632-860e-6fffa149a1f3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_019fceb7-66c5-729c-9c61-6885c84e8fb4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7798-a378-d37cbced0b78" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_019fceb7-66c5-729c-9c61-6885c84e8fb4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019fceb7-66c5-7e08-a04b-3766e559c0c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7798-a378-d37cbced0b78" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019fceb7-66c5-7e08-a04b-3766e559c0c6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice_019fceb7-66c5-7e21-b487-e3e9101bdfe4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7798-a378-d37cbced0b78" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice_019fceb7-66c5-7e21-b487-e3e9101bdfe4" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.arvinas.com/role/EquityScheduleofStockOptionActivityDetails" xlink:type="simple" xlink:href="arvn-20260930.xsd#EquityScheduleofStockOptionActivityDetails"/>
  <link:definitionLink xlink:role="http://www.arvinas.com/role/EquityScheduleofStockOptionActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-79e8-a635-b3b616cdb0d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-70ca-9617-846a9fedb0ce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-79e8-a635-b3b616cdb0d4" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-70ca-9617-846a9fedb0ce" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019fceb7-66c5-7001-9e62-3cdd37363ff4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-70ca-9617-846a9fedb0ce" xlink:to="loc_us-gaap_PlanNameAxis_019fceb7-66c5-7001-9e62-3cdd37363ff4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019fceb7-66c5-7001-9e62-3cdd37363ff4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019fceb7-66c5-7001-9e62-3cdd37363ff4" xlink:to="loc_us-gaap_PlanNameDomain_019fceb7-66c5-7001-9e62-3cdd37363ff4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019fceb7-66c5-7f03-a9dd-98b35b6998e1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019fceb7-66c5-7001-9e62-3cdd37363ff4" xlink:to="loc_us-gaap_PlanNameDomain_019fceb7-66c5-7f03-a9dd-98b35b6998e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_TwoThousandEighteenStockIncentivePlanMember_019fceb7-66c5-7a66-a6a6-2099397293a0" xlink:href="arvn-20260930.xsd#arvn_TwoThousandEighteenStockIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019fceb7-66c5-7f03-a9dd-98b35b6998e1" xlink:to="loc_arvn_TwoThousandEighteenStockIncentivePlanMember_019fceb7-66c5-7a66-a6a6-2099397293a0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019fceb7-66c5-75be-9dac-a5d502e70336" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-79e8-a635-b3b616cdb0d4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019fceb7-66c5-75be-9dac-a5d502e70336" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_019fceb7-66c5-7d6e-95d6-c0cc7ea9a377" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019fceb7-66c5-75be-9dac-a5d502e70336" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_019fceb7-66c5-7d6e-95d6-c0cc7ea9a377" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019fceb7-66c5-79b1-bba9-8a0ad882bfad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019fceb7-66c5-75be-9dac-a5d502e70336" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019fceb7-66c5-79b1-bba9-8a0ad882bfad" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_019fceb7-66c5-723d-86cc-b50b5d6a87b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019fceb7-66c5-75be-9dac-a5d502e70336" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_019fceb7-66c5-723d-86cc-b50b5d6a87b0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_019fceb7-66c5-72ee-b73d-d757e66f8f3a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019fceb7-66c5-75be-9dac-a5d502e70336" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_019fceb7-66c5-72ee-b73d-d757e66f8f3a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_019fceb7-66c5-72c7-a32d-21f08c605578" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_019fceb7-66c5-7666-bab0-fd7aa14da14d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-79e8-a635-b3b616cdb0d4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_019fceb7-66c5-7666-bab0-fd7aa14da14d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_019fceb7-66c5-7add-8e69-4a33682aa92c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-79e8-a635-b3b616cdb0d4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_019fceb7-66c5-7add-8e69-4a33682aa92c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_019fceb7-66c5-785f-8997-785bac4b1332" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-79e8-a635-b3b616cdb0d4" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_019fceb7-66c5-785f-8997-785bac4b1332" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_019fceb7-66c5-79ac-acbd-a35939ca0f3c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_019fceb7-66c5-785f-8997-785bac4b1332" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_019fceb7-66c5-79ac-acbd-a35939ca0f3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_019fceb7-66c5-78b7-a4f3-91f0368ba4fd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_019fceb7-66c5-785f-8997-785bac4b1332" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_019fceb7-66c5-78b7-a4f3-91f0368ba4fd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_019fceb7-66c5-7d45-8efb-93fc4a1576c1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_019fceb7-66c5-785f-8997-785bac4b1332" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_019fceb7-66c5-7d45-8efb-93fc4a1576c1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_019fceb7-66c5-73ae-8f53-e5fc1a6365d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_019fceb7-66c5-785f-8997-785bac4b1332" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_019fceb7-66c5-73ae-8f53-e5fc1a6365d9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_019fceb7-66c5-747d-9b39-ab599e0049bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_019fceb7-66c5-746e-b090-f42cc5089e9c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-79e8-a635-b3b616cdb0d4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_019fceb7-66c5-746e-b090-f42cc5089e9c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice_019fceb7-66c5-76df-bce0-5fd68c23fe6f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-79e8-a635-b3b616cdb0d4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice_019fceb7-66c5-76df-bce0-5fd68c23fe6f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_019fceb7-66c5-7323-8d33-217e56f7ebe9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-79e8-a635-b3b616cdb0d4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_019fceb7-66c5-7323-8d33-217e56f7ebe9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_019fceb7-66c5-78bf-83b7-119058854da7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_019fceb7-66c5-7323-8d33-217e56f7ebe9" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_019fceb7-66c5-78bf-83b7-119058854da7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_019fceb7-66c5-7468-8c16-a5cc15640d64" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_019fceb7-66c5-7323-8d33-217e56f7ebe9" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_019fceb7-66c5-7468-8c16-a5cc15640d64" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1_019fceb7-66c5-7b84-997e-c2bc7d51703d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_019fceb7-66c5-7323-8d33-217e56f7ebe9" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1_019fceb7-66c5-7b84-997e-c2bc7d51703d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_AggregateIntrinsicValueAbstract_019fceb7-66c5-7c94-a176-1fdaf49f3554" xlink:href="arvn-20260930.xsd#arvn_AggregateIntrinsicValueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-79e8-a635-b3b616cdb0d4" xlink:to="loc_arvn_AggregateIntrinsicValueAbstract_019fceb7-66c5-7c94-a176-1fdaf49f3554" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_019fceb7-66c5-7669-8fce-aa0edb60f00b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_AggregateIntrinsicValueAbstract_019fceb7-66c5-7c94-a176-1fdaf49f3554" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_019fceb7-66c5-7669-8fce-aa0edb60f00b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_019fceb7-66c5-7f4a-9596-3dd5fa560f9f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_AggregateIntrinsicValueAbstract_019fceb7-66c5-7c94-a176-1fdaf49f3554" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_019fceb7-66c5-7f4a-9596-3dd5fa560f9f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_019fceb7-66c5-7629-aab1-f5fcb3ccdf3c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_AggregateIntrinsicValueAbstract_019fceb7-66c5-7c94-a176-1fdaf49f3554" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_019fceb7-66c5-7629-aab1-f5fcb3ccdf3c" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.arvinas.com/role/EquityScheduleofRestrictedStockDetails" xlink:type="simple" xlink:href="arvn-20260930.xsd#EquityScheduleofRestrictedStockDetails"/>
  <link:definitionLink xlink:role="http://www.arvinas.com/role/EquityScheduleofRestrictedStockDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7094-9dc7-96c302961958" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-7d1f-88da-d5e0a654c5bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7094-9dc7-96c302961958" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-7d1f-88da-d5e0a654c5bb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019fceb7-66c5-7970-bbe8-1cac8f63b9f4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-7d1f-88da-d5e0a654c5bb" xlink:to="loc_us-gaap_PlanNameAxis_019fceb7-66c5-7970-bbe8-1cac8f63b9f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019fceb7-66c5-7970-bbe8-1cac8f63b9f4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019fceb7-66c5-7970-bbe8-1cac8f63b9f4" xlink:to="loc_us-gaap_PlanNameDomain_019fceb7-66c5-7970-bbe8-1cac8f63b9f4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019fceb7-66c5-798a-888c-9549c8bdc8da" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019fceb7-66c5-7970-bbe8-1cac8f63b9f4" xlink:to="loc_us-gaap_PlanNameDomain_019fceb7-66c5-798a-888c-9549c8bdc8da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_TwoThousandEighteenStockIncentivePlanMember_019fceb7-66c5-7082-b98d-1c244276f842" xlink:href="arvn-20260930.xsd#arvn_TwoThousandEighteenStockIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019fceb7-66c5-798a-888c-9549c8bdc8da" xlink:to="loc_arvn_TwoThousandEighteenStockIncentivePlanMember_019fceb7-66c5-7082-b98d-1c244276f842" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019fceb7-66c5-7a3f-842f-b9c3496c21ca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019fceb7-66c5-7d1f-88da-d5e0a654c5bb" xlink:to="loc_us-gaap_AwardTypeAxis_019fceb7-66c5-7a3f-842f-b9c3496c21ca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fceb7-66c5-7a3f-842f-b9c3496c21ca_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019fceb7-66c5-7a3f-842f-b9c3496c21ca" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fceb7-66c5-7a3f-842f-b9c3496c21ca_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fceb7-66c5-724f-b024-0f1a2bcaf40c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019fceb7-66c5-7a3f-842f-b9c3496c21ca" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fceb7-66c5-724f-b024-0f1a2bcaf40c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019fceb7-66c5-7bf5-af7e-d7d3afaec818" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019fceb7-66c5-724f-b024-0f1a2bcaf40c" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019fceb7-66c5-7bf5-af7e-d7d3afaec818" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019fceb7-66c5-763f-b1ce-e88b187762b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7094-9dc7-96c302961958" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019fceb7-66c5-763f-b1ce-e88b187762b8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019fceb7-66c5-7c8d-b25f-c217e04ad2ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019fceb7-66c5-763f-b1ce-e88b187762b8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019fceb7-66c5-7c8d-b25f-c217e04ad2ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019fceb7-66c5-7230-8f3f-7a0fdb2e114e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019fceb7-66c5-763f-b1ce-e88b187762b8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019fceb7-66c5-7230-8f3f-7a0fdb2e114e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019fceb7-66c5-7cac-8194-85490c26671f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019fceb7-66c5-763f-b1ce-e88b187762b8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019fceb7-66c5-7cac-8194-85490c26671f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019fceb7-66c5-7796-9b07-610773396d25" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019fceb7-66c5-763f-b1ce-e88b187762b8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019fceb7-66c5-7796-9b07-610773396d25" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019fceb7-66c5-7f27-9b27-b78d842f6ed8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019fceb7-66c5-7cc3-8d88-09fd8a409b59" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019fceb7-66c5-7094-9dc7-96c302961958" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019fceb7-66c5-7cc3-8d88-09fd8a409b59" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019fceb7-66c5-72d0-b2c9-66115e6200a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019fceb7-66c5-7cc3-8d88-09fd8a409b59" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019fceb7-66c5-72d0-b2c9-66115e6200a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019fceb7-66c5-7094-8257-cf8c4317dfd0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019fceb7-66c5-7cc3-8d88-09fd8a409b59" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019fceb7-66c5-7094-8257-cf8c4317dfd0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019fceb7-66c5-738a-b257-cadef80df45f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019fceb7-66c5-7cc3-8d88-09fd8a409b59" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019fceb7-66c5-738a-b257-cadef80df45f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019fceb7-66c5-785a-a280-83e74cc5e010" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019fceb7-66c5-7cc3-8d88-09fd8a409b59" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019fceb7-66c5-785a-a280-83e74cc5e010" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019fceb7-66c5-76fe-9525-d71d8fcdf492" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.arvinas.com/role/LossEarningsPerCommonShareSecuritiesExcludedFromComputationofDilutedNetLossPerCommonShareDetails" xlink:type="simple" xlink:href="arvn-20260930.xsd#LossEarningsPerCommonShareSecuritiesExcludedFromComputationofDilutedNetLossPerCommonShareDetails"/>
  <link:definitionLink xlink:role="http://www.arvinas.com/role/LossEarningsPerCommonShareSecuritiesExcludedFromComputationofDilutedNetLossPerCommonShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fceb7-66c5-7c75-9bd4-13810d35935e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019fceb7-66c5-7adb-bf85-ded07ec80145" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fceb7-66c5-7c75-9bd4-13810d35935e" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019fceb7-66c5-7adb-bf85-ded07ec80145" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019fceb7-66c5-7378-9ecd-26c41591041d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019fceb7-66c5-7adb-bf85-ded07ec80145" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019fceb7-66c5-7378-9ecd-26c41591041d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fceb7-66c5-7378-9ecd-26c41591041d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019fceb7-66c5-7378-9ecd-26c41591041d" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fceb7-66c5-7378-9ecd-26c41591041d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fceb7-66c5-7758-bc93-383358519729" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019fceb7-66c5-7378-9ecd-26c41591041d" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fceb7-66c5-7758-bc93-383358519729" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019fceb7-66c5-7255-b8e7-3790c7a7b6af" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fceb7-66c5-7758-bc93-383358519729" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019fceb7-66c5-7255-b8e7-3790c7a7b6af" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019fceb7-66c5-72d0-8e85-1b8bf6e27d6c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fceb7-66c5-7758-bc93-383358519729" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019fceb7-66c5-72d0-8e85-1b8bf6e27d6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019fceb7-66c5-72fc-adc1-5382333a0f66" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fceb7-66c5-7c75-9bd4-13810d35935e" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019fceb7-66c5-72fc-adc1-5382333a0f66" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.arvinas.com/role/CommitmentsandContingenciesDetails" xlink:type="simple" xlink:href="arvn-20260930.xsd#CommitmentsandContingenciesDetails"/>
  <link:definitionLink xlink:role="http://www.arvinas.com/role/CommitmentsandContingenciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_arvn_CommitmentsAndContingenciesLineItems_019fceb7-66c5-7498-b04a-92b73385b6a3" xlink:href="arvn-20260930.xsd#arvn_CommitmentsAndContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_CommitmentsAndContingenciesTable_019fceb7-66c5-75fb-a739-53ea895df3d8" xlink:href="arvn-20260930.xsd#arvn_CommitmentsAndContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_arvn_CommitmentsAndContingenciesLineItems_019fceb7-66c5-7498-b04a-92b73385b6a3" xlink:to="loc_arvn_CommitmentsAndContingenciesTable_019fceb7-66c5-75fb-a739-53ea895df3d8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019fceb7-66c5-7313-9ff8-67c4db99d8e6" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_arvn_CommitmentsAndContingenciesTable_019fceb7-66c5-75fb-a739-53ea895df3d8" xlink:to="loc_srt_CounterpartyNameAxis_019fceb7-66c5-7313-9ff8-67c4db99d8e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-66c5-7313-9ff8-67c4db99d8e6_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019fceb7-66c5-7313-9ff8-67c4db99d8e6" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-66c5-7313-9ff8-67c4db99d8e6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-66c5-7f7c-8ce9-17714f2f9d70" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019fceb7-66c5-7313-9ff8-67c4db99d8e6" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-66c5-7f7c-8ce9-17714f2f9d70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_YaleUniversityMember_019fceb7-66c5-7364-8aef-b06ccfc98f8d" xlink:href="arvn-20260930.xsd#arvn_YaleUniversityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019fceb7-66c5-7f7c-8ce9-17714f2f9d70" xlink:to="loc_arvn_YaleUniversityMember_019fceb7-66c5-7364-8aef-b06ccfc98f8d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_019fceb7-66c5-7fe2-a1bd-fe747749ed13" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_arvn_CommitmentsAndContingenciesTable_019fceb7-66c5-75fb-a739-53ea895df3d8" xlink:to="loc_us-gaap_TypeOfArrangementAxis_019fceb7-66c5-7fe2-a1bd-fe747749ed13" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-66c5-7fe2-a1bd-fe747749ed13_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_019fceb7-66c5-7fe2-a1bd-fe747749ed13" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-66c5-7fe2-a1bd-fe747749ed13_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-66c5-7bfe-856e-3434a629a902" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_019fceb7-66c5-7fe2-a1bd-fe747749ed13" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-66c5-7bfe-856e-3434a629a902" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_UpfrontPaymentForAmendedLicenseAgreementAndNovartisLicenseAndAssetAgreementsMember_019fceb7-66c5-7d37-8ee7-475d834c4a68" xlink:href="arvn-20260930.xsd#arvn_UpfrontPaymentForAmendedLicenseAgreementAndNovartisLicenseAndAssetAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-66c5-7bfe-856e-3434a629a902" xlink:to="loc_arvn_UpfrontPaymentForAmendedLicenseAgreementAndNovartisLicenseAndAssetAgreementsMember_019fceb7-66c5-7d37-8ee7-475d834c4a68" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_MilestonePaymentOnFirstAnniversaryOfSigningMember_019fceb7-66c5-7cfb-acbc-8ec27b15f129" xlink:href="arvn-20260930.xsd#arvn_MilestonePaymentOnFirstAnniversaryOfSigningMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-66c5-7bfe-856e-3434a629a902" xlink:to="loc_arvn_MilestonePaymentOnFirstAnniversaryOfSigningMember_019fceb7-66c5-7cfb-acbc-8ec27b15f129" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_MilestonePaymentUponApprovalOfFirstAndSecondRoyaltyProductsMember_019fceb7-66c5-7055-8691-775a19dcb36a" xlink:href="arvn-20260930.xsd#arvn_MilestonePaymentUponApprovalOfFirstAndSecondRoyaltyProductsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-66c5-7bfe-856e-3434a629a902" xlink:to="loc_arvn_MilestonePaymentUponApprovalOfFirstAndSecondRoyaltyProductsMember_019fceb7-66c5-7055-8691-775a19dcb36a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_SuccessBasedMilestonePaymentsMember_019fceb7-66c5-7694-99c0-26123e62cd5a" xlink:href="arvn-20260930.xsd#arvn_SuccessBasedMilestonePaymentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019fceb7-66c5-7bfe-856e-3434a629a902" xlink:to="loc_arvn_SuccessBasedMilestonePaymentsMember_019fceb7-66c5-7694-99c0-26123e62cd5a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019fceb7-66c5-70fa-8023-044f429d0e9b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_arvn_CommitmentsAndContingenciesTable_019fceb7-66c5-75fb-a739-53ea895df3d8" xlink:to="loc_srt_RangeAxis_019fceb7-66c5-70fa-8023-044f429d0e9b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fceb7-66c5-70fa-8023-044f429d0e9b_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019fceb7-66c5-70fa-8023-044f429d0e9b" xlink:to="loc_srt_RangeMember_019fceb7-66c5-70fa-8023-044f429d0e9b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fceb7-66c5-75b8-882f-8b027c53b370" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019fceb7-66c5-70fa-8023-044f429d0e9b" xlink:to="loc_srt_RangeMember_019fceb7-66c5-75b8-882f-8b027c53b370" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019fceb7-66c5-7699-a6ca-5f1e2d1fe210" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019fceb7-66c5-75b8-882f-8b027c53b370" xlink:to="loc_srt_MaximumMember_019fceb7-66c5-7699-a6ca-5f1e2d1fe210" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019fceb7-66c5-7dbf-82bb-155e14f7a51f" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019fceb7-66c5-75b8-882f-8b027c53b370" xlink:to="loc_srt_MinimumMember_019fceb7-66c5-7dbf-82bb-155e14f7a51f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019fceb7-66c5-7c49-877b-958dbaa0f302" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_arvn_CommitmentsAndContingenciesTable_019fceb7-66c5-75fb-a739-53ea895df3d8" xlink:to="loc_srt_ProductOrServiceAxis_019fceb7-66c5-7c49-877b-958dbaa0f302" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-7c49-877b-958dbaa0f302_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019fceb7-66c5-7c49-877b-958dbaa0f302" xlink:to="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-7c49-877b-958dbaa0f302_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-7887-a688-d79d8eb8a911" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019fceb7-66c5-7c49-877b-958dbaa0f302" xlink:to="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-7887-a688-d79d8eb8a911" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_LicenseFirstLicensedProductMember_019fceb7-66c5-7adb-b983-dc6d3b9d1938" xlink:href="arvn-20260930.xsd#arvn_LicenseFirstLicensedProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-7887-a688-d79d8eb8a911" xlink:to="loc_arvn_LicenseFirstLicensedProductMember_019fceb7-66c5-7adb-b983-dc6d3b9d1938" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_LicenseSecondLicensedProductMember_019fceb7-66c5-7183-be01-05acfb567448" xlink:href="arvn-20260930.xsd#arvn_LicenseSecondLicensedProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-7887-a688-d79d8eb8a911" xlink:to="loc_arvn_LicenseSecondLicensedProductMember_019fceb7-66c5-7183-be01-05acfb567448" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_PaymentsForCollaboration_019fceb7-66c5-7bdc-b89b-857080348377" xlink:href="arvn-20260930.xsd#arvn_PaymentsForCollaboration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_CommitmentsAndContingenciesLineItems_019fceb7-66c5-7498-b04a-92b73385b6a3" xlink:to="loc_arvn_PaymentsForCollaboration_019fceb7-66c5-7bdc-b89b-857080348377" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_CollaborativeArrangementRightsAndObligationsMilestonePayment_019fceb7-66c5-7847-b156-ecf5ca560166" xlink:href="arvn-20260930.xsd#arvn_CollaborativeArrangementRightsAndObligationsMilestonePayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_CommitmentsAndContingenciesLineItems_019fceb7-66c5-7498-b04a-92b73385b6a3" xlink:to="loc_arvn_CollaborativeArrangementRightsAndObligationsMilestonePayment_019fceb7-66c5-7847-b156-ecf5ca560166" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_AnnualLicenseFeePayment_019fceb7-66c5-7c08-8133-bd44bc15aa49" xlink:href="arvn-20260930.xsd#arvn_AnnualLicenseFeePayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_CommitmentsAndContingenciesLineItems_019fceb7-66c5-7498-b04a-92b73385b6a3" xlink:to="loc_arvn_AnnualLicenseFeePayment_019fceb7-66c5-7c08-8133-bd44bc15aa49" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_NumberOfLicensedProducts_019fceb7-66c5-7596-9296-4ffb51350262" xlink:href="arvn-20260930.xsd#arvn_NumberOfLicensedProducts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_CommitmentsAndContingenciesLineItems_019fceb7-66c5-7498-b04a-92b73385b6a3" xlink:to="loc_arvn_NumberOfLicensedProducts_019fceb7-66c5-7596-9296-4ffb51350262" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_RequiredMilestonePayments_019fceb7-66c5-7871-b90e-887335964855" xlink:href="arvn-20260930.xsd#arvn_RequiredMilestonePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_CommitmentsAndContingenciesLineItems_019fceb7-66c5-7498-b04a-92b73385b6a3" xlink:to="loc_arvn_RequiredMilestonePayments_019fceb7-66c5-7871-b90e-887335964855" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRoyalties_019fceb7-66c5-7a03-9f42-421bf9128a4c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForRoyalties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_CommitmentsAndContingenciesLineItems_019fceb7-66c5-7498-b04a-92b73385b6a3" xlink:to="loc_us-gaap_PaymentsForRoyalties_019fceb7-66c5-7a03-9f42-421bf9128a4c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_CostOfLicenseRevenueOperatingExpense_019fceb7-66c5-705f-a258-7e333fe3c51d" xlink:href="arvn-20260930.xsd#arvn_CostOfLicenseRevenueOperatingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_arvn_CommitmentsAndContingenciesLineItems_019fceb7-66c5-7498-b04a-92b73385b6a3" xlink:to="loc_arvn_CostOfLicenseRevenueOperatingExpense_019fceb7-66c5-705f-a258-7e333fe3c51d" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.arvinas.com/role/RelatedPartyTransactionsDetails" xlink:type="simple" xlink:href="arvn-20260930.xsd#RelatedPartyTransactionsDetails"/>
  <link:definitionLink xlink:role="http://www.arvinas.com/role/RelatedPartyTransactionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_019fceb7-66c5-7e72-9444-aa2bfed8118d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019fceb7-66c5-707e-8e65-084391e3d5ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019fceb7-66c5-7e72-9444-aa2bfed8118d" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019fceb7-66c5-707e-8e65-084391e3d5ba" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionAxis_019fceb7-66c5-77ba-ac23-4cf6f753d4ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019fceb7-66c5-707e-8e65-084391e3d5ba" xlink:to="loc_us-gaap_RelatedPartyTransactionAxis_019fceb7-66c5-77ba-ac23-4cf6f753d4ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_019fceb7-66c5-77ba-ac23-4cf6f753d4ee_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_019fceb7-66c5-77ba-ac23-4cf6f753d4ee" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_019fceb7-66c5-77ba-ac23-4cf6f753d4ee_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_019fceb7-66c5-7856-8e4b-43915171349d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_019fceb7-66c5-77ba-ac23-4cf6f753d4ee" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_019fceb7-66c5-7856-8e4b-43915171349d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ConsultingAgreementLumpSumPaymentMember_019fceb7-66c5-7261-b27b-e54ffdfec4b4" xlink:href="arvn-20260930.xsd#arvn_ConsultingAgreementLumpSumPaymentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_019fceb7-66c5-7856-8e4b-43915171349d" xlink:to="loc_arvn_ConsultingAgreementLumpSumPaymentMember_019fceb7-66c5-7261-b27b-e54ffdfec4b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ConsultingAgreementCOBRAReimbursementMember_019fceb7-66c5-7c35-974d-1dffe6419a31" xlink:href="arvn-20260930.xsd#arvn_ConsultingAgreementCOBRAReimbursementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_019fceb7-66c5-7856-8e4b-43915171349d" xlink:to="loc_arvn_ConsultingAgreementCOBRAReimbursementMember_019fceb7-66c5-7c35-974d-1dffe6419a31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019fceb7-66c5-70ae-999f-526fa47dbc89" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019fceb7-66c5-707e-8e65-084391e3d5ba" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019fceb7-66c5-70ae-999f-526fa47dbc89" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019fceb7-66c5-70ae-999f-526fa47dbc89_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019fceb7-66c5-70ae-999f-526fa47dbc89" xlink:to="loc_us-gaap_RelatedPartyDomain_019fceb7-66c5-70ae-999f-526fa47dbc89_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019fceb7-66c5-75d5-bd51-113d972fc747" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019fceb7-66c5-70ae-999f-526fa47dbc89" xlink:to="loc_us-gaap_RelatedPartyDomain_019fceb7-66c5-75d5-bd51-113d972fc747" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_DirectorMember_019fceb7-66c5-7bde-90a7-5a48bbcd974a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_DirectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019fceb7-66c5-75d5-bd51-113d972fc747" xlink:to="loc_srt_DirectorMember_019fceb7-66c5-7bde-90a7-5a48bbcd974a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction_019fceb7-66c5-774d-9b15-462e44e7eb45" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionAmountsOfTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019fceb7-66c5-7e72-9444-aa2bfed8118d" xlink:to="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction_019fceb7-66c5-774d-9b15-462e44e7eb45" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_RelatedPartyHourlyRate_019fceb7-66c5-704d-a6eb-c1812c6e8c77" xlink:href="arvn-20260930.xsd#arvn_RelatedPartyHourlyRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019fceb7-66c5-7e72-9444-aa2bfed8118d" xlink:to="loc_arvn_RelatedPartyHourlyRate_019fceb7-66c5-704d-a6eb-c1812c6e8c77" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_RelatedPartyOvertimeThresholdMinimumNumberOfHoursInAMonth_019fceb7-66c5-7e95-95bb-d28578c452e8" xlink:href="arvn-20260930.xsd#arvn_RelatedPartyOvertimeThresholdMinimumNumberOfHoursInAMonth"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019fceb7-66c5-7e72-9444-aa2bfed8118d" xlink:to="loc_arvn_RelatedPartyOvertimeThresholdMinimumNumberOfHoursInAMonth_019fceb7-66c5-7e95-95bb-d28578c452e8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_019fceb7-66c5-7d9b-b5ce-20c534ca2f55" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019fceb7-66c5-7e72-9444-aa2bfed8118d" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_019fceb7-66c5-7d9b-b5ce-20c534ca2f55" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.arvinas.com/role/RestructuringActivityDetails" xlink:type="simple" xlink:href="arvn-20260930.xsd#RestructuringActivityDetails"/>
  <link:definitionLink xlink:role="http://www.arvinas.com/role/RestructuringActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019fceb7-66c5-7a50-8ebb-a3c6094fc584" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019fceb7-66c5-700a-bb87-986db8c1b419" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019fceb7-66c5-7a50-8ebb-a3c6094fc584" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019fceb7-66c5-700a-bb87-986db8c1b419" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019fceb7-66c5-7c7c-bd35-4f5d75183f1d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019fceb7-66c5-700a-bb87-986db8c1b419" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019fceb7-66c5-7c7c-bd35-4f5d75183f1d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_019fceb7-66c5-710c-af16-c53e23e6e3e1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019fceb7-66c5-700a-bb87-986db8c1b419" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_019fceb7-66c5-710c-af16-c53e23e6e3e1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019fceb7-66c5-710c-af16-c53e23e6e3e1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019fceb7-66c5-710c-af16-c53e23e6e3e1" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019fceb7-66c5-710c-af16-c53e23e6e3e1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019fceb7-66c5-7077-9cc6-a85dffcbfd2e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019fceb7-66c5-710c-af16-c53e23e6e3e1" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019fceb7-66c5-7077-9cc6-a85dffcbfd2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeSeveranceMember_019fceb7-66c5-75be-b97e-d79eb409893c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeSeveranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019fceb7-66c5-7077-9cc6-a85dffcbfd2e" xlink:to="loc_us-gaap_EmployeeSeveranceMember_019fceb7-66c5-75be-b97e-d79eb409893c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_StockCompensationAndBonusExpenseMember_019fceb7-66c5-7f2f-868e-c70bae3fb2f1" xlink:href="arvn-20260930.xsd#arvn_StockCompensationAndBonusExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019fceb7-66c5-7077-9cc6-a85dffcbfd2e" xlink:to="loc_arvn_StockCompensationAndBonusExpenseMember_019fceb7-66c5-7f2f-868e-c70bae3fb2f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminatedPeriodPercent_019fceb7-66c5-77c9-96aa-85c5c3f89cc5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminatedPeriodPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019fceb7-66c5-7a50-8ebb-a3c6094fc584" xlink:to="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminatedPeriodPercent_019fceb7-66c5-77c9-96aa-85c5c3f89cc5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_019fceb7-66c5-7015-a426-f0a281e92c08" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019fceb7-66c5-7a50-8ebb-a3c6094fc584" xlink:to="loc_us-gaap_RestructuringCharges_019fceb7-66c5-7015-a426-f0a281e92c08" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_019fceb7-66c5-7bcc-8549-441f36f23b1f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringReserve"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019fceb7-66c5-7a50-8ebb-a3c6094fc584" xlink:to="loc_us-gaap_RestructuringReserve_019fceb7-66c5-7bcc-8549-441f36f23b1f" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.arvinas.com/role/RestructuringActivityDetails_1" xlink:type="simple" xlink:href="arvn-20260930.xsd#RestructuringActivityDetails_1"/>
  <link:definitionLink xlink:role="http://www.arvinas.com/role/RestructuringActivityDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019fceb7-66c5-7a50-8ebb-a3c6094fc584" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019fceb7-66c5-700a-bb87-986db8c1b419" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019fceb7-66c5-7a50-8ebb-a3c6094fc584" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019fceb7-66c5-700a-bb87-986db8c1b419" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_019fceb7-66c5-710c-af16-c53e23e6e3e1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019fceb7-66c5-700a-bb87-986db8c1b419" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_019fceb7-66c5-710c-af16-c53e23e6e3e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019fceb7-66c5-710c-af16-c53e23e6e3e1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019fceb7-66c5-710c-af16-c53e23e6e3e1" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019fceb7-66c5-710c-af16-c53e23e6e3e1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019fceb7-66c5-7077-9cc6-a85dffcbfd2e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019fceb7-66c5-710c-af16-c53e23e6e3e1" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019fceb7-66c5-7077-9cc6-a85dffcbfd2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeSeveranceMember_019fceb7-66c5-75be-b97e-d79eb409893c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeSeveranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019fceb7-66c5-7077-9cc6-a85dffcbfd2e" xlink:to="loc_us-gaap_EmployeeSeveranceMember_019fceb7-66c5-75be-b97e-d79eb409893c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_StockCompensationAndBonusExpenseMember_019fceb7-66c5-7f2f-868e-c70bae3fb2f1" xlink:href="arvn-20260930.xsd#arvn_StockCompensationAndBonusExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019fceb7-66c5-7077-9cc6-a85dffcbfd2e" xlink:to="loc_arvn_StockCompensationAndBonusExpenseMember_019fceb7-66c5-7f2f-868e-c70bae3fb2f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminatedPeriodPercent_019fceb7-66c5-77c9-96aa-85c5c3f89cc5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminatedPeriodPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019fceb7-66c5-7a50-8ebb-a3c6094fc584" xlink:to="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminatedPeriodPercent_019fceb7-66c5-77c9-96aa-85c5c3f89cc5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_019fceb7-66c5-7015-a426-f0a281e92c08" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019fceb7-66c5-7a50-8ebb-a3c6094fc584" xlink:to="loc_us-gaap_RestructuringCharges_019fceb7-66c5-7015-a426-f0a281e92c08" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_019fceb7-66c5-7bcc-8549-441f36f23b1f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringReserve"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019fceb7-66c5-7a50-8ebb-a3c6094fc584" xlink:to="loc_us-gaap_RestructuringReserve_019fceb7-66c5-7bcc-8549-441f36f23b1f" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.arvinas.com/role/SegmentInformationScheduleofReportableSegmentFinancialInformationDetails" xlink:type="simple" xlink:href="arvn-20260930.xsd#SegmentInformationScheduleofReportableSegmentFinancialInformationDetails"/>
  <link:definitionLink xlink:role="http://www.arvinas.com/role/SegmentInformationScheduleofReportableSegmentFinancialInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019fceb7-66c5-7641-99db-18b11f2e7578" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019fceb7-66c5-78a9-9d00-8dec3e838752" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fceb7-66c5-7641-99db-18b11f2e7578" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019fceb7-66c5-78a9-9d00-8dec3e838752" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019fceb7-66c5-738c-b1a1-7a4e8dd8850f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019fceb7-66c5-78a9-9d00-8dec3e838752" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019fceb7-66c5-738c-b1a1-7a4e8dd8850f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019fceb7-66c5-738c-b1a1-7a4e8dd8850f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019fceb7-66c5-738c-b1a1-7a4e8dd8850f" xlink:to="loc_us-gaap_SegmentDomain_019fceb7-66c5-738c-b1a1-7a4e8dd8850f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019fceb7-66c5-726d-b828-277b37e4e379" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019fceb7-66c5-738c-b1a1-7a4e8dd8850f" xlink:to="loc_us-gaap_SegmentDomain_019fceb7-66c5-726d-b828-277b37e4e379" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ReportableSegmentMember_019fceb7-66c5-7e3c-b71c-bb4af8298075" xlink:href="arvn-20260930.xsd#arvn_ReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019fceb7-66c5-726d-b828-277b37e4e379" xlink:to="loc_arvn_ReportableSegmentMember_019fceb7-66c5-7e3c-b71c-bb4af8298075" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019fceb7-66c5-712f-990a-ead8802fcd0c" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019fceb7-66c5-78a9-9d00-8dec3e838752" xlink:to="loc_srt_ProductOrServiceAxis_019fceb7-66c5-712f-990a-ead8802fcd0c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-712f-990a-ead8802fcd0c_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019fceb7-66c5-712f-990a-ead8802fcd0c" xlink:to="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-712f-990a-ead8802fcd0c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-7879-be90-c9ffe123a45b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019fceb7-66c5-712f-990a-ead8802fcd0c" xlink:to="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-7879-be90-c9ffe123a45b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ARV471Member_019fceb7-66c5-7ef1-b992-0fe269548cc0" xlink:href="arvn-20260930.xsd#arvn_ARV471Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-7879-be90-c9ffe123a45b" xlink:to="loc_arvn_ARV471Member_019fceb7-66c5-7ef1-b992-0fe269548cc0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ARV806Member_019fceb7-66c5-7c35-847d-2fae944400b2" xlink:href="arvn-20260930.xsd#arvn_ARV806Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-7879-be90-c9ffe123a45b" xlink:to="loc_arvn_ARV806Member_019fceb7-66c5-7c35-847d-2fae944400b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ARV102Member_019fceb7-66c5-736c-8110-5e7fcbbccf7f" xlink:href="arvn-20260930.xsd#arvn_ARV102Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-7879-be90-c9ffe123a45b" xlink:to="loc_arvn_ARV102Member_019fceb7-66c5-736c-8110-5e7fcbbccf7f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ARV393Member_019fceb7-66c5-7a46-9839-7452d5e0a16c" xlink:href="arvn-20260930.xsd#arvn_ARV393Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-7879-be90-c9ffe123a45b" xlink:to="loc_arvn_ARV393Member_019fceb7-66c5-7a46-9839-7452d5e0a16c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ARV027Member_019fceb7-66c5-73dc-b84a-f8875024cbcf" xlink:href="arvn-20260930.xsd#arvn_ARV027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-7879-be90-c9ffe123a45b" xlink:to="loc_arvn_ARV027Member_019fceb7-66c5-73dc-b84a-f8875024cbcf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ARV6723Member_01a15567-d4f2-718f-b226-2f55552241c5" xlink:href="arvn-20260930.xsd#arvn_ARV6723Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-7879-be90-c9ffe123a45b" xlink:to="loc_arvn_ARV6723Member_01a15567-d4f2-718f-b226-2f55552241c5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ARV110Member_019fceb7-66c5-760f-9e00-e7a6c2206063" xlink:href="arvn-20260930.xsd#arvn_ARV110Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-7879-be90-c9ffe123a45b" xlink:to="loc_arvn_ARV110Member_019fceb7-66c5-760f-9e00-e7a6c2206063" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ARV766Member_01a15569-126d-78e1-b12b-933f747a191d" xlink:href="arvn-20260930.xsd#arvn_ARV766Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-7879-be90-c9ffe123a45b" xlink:to="loc_arvn_ARV766Member_01a15569-126d-78e1-b12b-933f747a191d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_OtherProgramsMember_019fceb7-66c5-73bc-bf07-941717ec9739" xlink:href="arvn-20260930.xsd#arvn_OtherProgramsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019fceb7-66c5-7879-be90-c9ffe123a45b" xlink:to="loc_arvn_OtherProgramsMember_019fceb7-66c5-73bc-bf07-941717ec9739" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019fceb7-66c5-74ff-9fe7-f2a9abddbc4a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fceb7-66c5-7641-99db-18b11f2e7578" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019fceb7-66c5-74ff-9fe7-f2a9abddbc4a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019fceb7-66c5-7075-af6b-7cf22db911b5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fceb7-66c5-7641-99db-18b11f2e7578" xlink:to="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019fceb7-66c5-7075-af6b-7cf22db911b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_CostOfLicenseRevenueOperatingExpense_019fceb7-66c5-7076-8715-8f481fc75567" xlink:href="arvn-20260930.xsd#arvn_CostOfLicenseRevenueOperatingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019fceb7-66c5-7075-af6b-7cf22db911b5" xlink:to="loc_arvn_CostOfLicenseRevenueOperatingExpense_019fceb7-66c5-7076-8715-8f481fc75567" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ResearchAndDevelopmentExpenseProgramSpecific_019fceb7-66c5-704a-b41d-b954a878ebb7" xlink:href="arvn-20260930.xsd#arvn_ResearchAndDevelopmentExpenseProgramSpecific"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019fceb7-66c5-7075-af6b-7cf22db911b5" xlink:to="loc_arvn_ResearchAndDevelopmentExpenseProgramSpecific_019fceb7-66c5-704a-b41d-b954a878ebb7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_arvn_ResearchAndDevelopmentExpenseNonProgramSpecific_019fceb7-66c5-7404-a575-a78c9af2c9a1" xlink:href="arvn-20260930.xsd#arvn_ResearchAndDevelopmentExpenseNonProgramSpecific"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019fceb7-66c5-7075-af6b-7cf22db911b5" xlink:to="loc_arvn_ResearchAndDevelopmentExpenseNonProgramSpecific_019fceb7-66c5-7404-a575-a78c9af2c9a1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LaborAndRelatedExpense_019fceb7-66c5-727e-bd4d-f40ae4ceb3cf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LaborAndRelatedExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019fceb7-66c5-7075-af6b-7cf22db911b5" xlink:to="loc_us-gaap_LaborAndRelatedExpense_019fceb7-66c5-727e-bd4d-f40ae4ceb3cf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherResearchAndDevelopmentExpense_019fceb7-66c5-7604-85d8-9128ad108c5c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019fceb7-66c5-7075-af6b-7cf22db911b5" xlink:to="loc_us-gaap_OtherResearchAndDevelopmentExpense_019fceb7-66c5-7604-85d8-9128ad108c5c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_019fceb7-66c5-7d03-80ee-559387108d87" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019fceb7-66c5-7075-af6b-7cf22db911b5" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_019fceb7-66c5-7d03-80ee-559387108d87" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_019fceb7-66c5-79ce-9438-2d66bc1b79ab" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019fceb7-66c5-7075-af6b-7cf22db911b5" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_019fceb7-66c5-79ce-9438-2d66bc1b79ab" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherItemAmount_019fceb7-66c5-7a66-8d8f-95c38b0422d7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingOtherItemAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019fceb7-66c5-7075-af6b-7cf22db911b5" xlink:to="loc_us-gaap_SegmentReportingOtherItemAmount_019fceb7-66c5-7a66-8d8f-95c38b0422d7" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019fceb7-66c5-78d4-bfff-ee14b6173164" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019fceb7-66c5-7075-af6b-7cf22db911b5" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019fceb7-66c5-78d4-bfff-ee14b6173164" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInterest_019fceb7-66c5-7245-8046-8e3b518735d0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentIncomeInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fceb7-66c5-7641-99db-18b11f2e7578" xlink:to="loc_us-gaap_InvestmentIncomeInterest_019fceb7-66c5-7245-8046-8e3b518735d0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019fceb7-66c5-7e75-b9bf-937eed28fec0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019fceb7-66c5-7641-99db-18b11f2e7578" xlink:to="loc_us-gaap_NetIncomeLoss_019fceb7-66c5-7e75-b9bf-937eed28fec0" xlink:type="arc" order="3"/>
  </link:definitionLink>
</link:linkbase>
