<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2013-02-22</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000899629</issuerCik>
        <issuerName>ACADIA REALTY TRUST</issuerName>
        <issuerTradingSymbol>AKR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001218913</rptOwnerCik>
            <rptOwnerName>NAPOLITANO JOSEPH</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ACADIA REALTY TRUST</rptOwnerStreet1>
            <rptOwnerStreet2>1311 MAMARONECK AVENUE, SUITE 260</rptOwnerStreet2>
            <rptOwnerCity>WHITE PLAINS</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10605</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Sr. Vice President</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Limited Partnership Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>26.59</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2013-02-22</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>25950</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Shares of Beneficial Interest</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>25950</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>85690</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On February 22, 2013, Mr. Napolitano was awarded these restricted limited partnership units in Acadia Realty Limited Partnership (&quot;LTIP Units&quot;).  Of these 25,950 LTIP Units, 21,061 shall vest subject to the following schedule:  equal amounts shall vest on January 6, 2014, and on each of the first, second, third and fourth anniversaries thereof, provided that Mr. Napolitano continues to be employed by Acadia Realty Trust (the &quot;Company&quot;) through the vesting date in question.  Of the remaining 4,889 LTIP Units, 50% shall vest subject to the same schedule and to Mr. Napolitano's continued employment by the Company, and 50% shall vest subject to the same schedule,  Mr. Napolitano's continued employment by the Company and the Company achieving certain annual and cumulative benchmarks established by the Company's Board of Trustees.</footnote>
        <footnote id="F2">This number represents the total number of LTIP Units (vested and unvested) held by Mr. Napolitano.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Joseph Napolitano</signatureName>
        <signatureDate>2013-02-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
