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

    <schemaVersion>X0304</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2012-02-17</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001219735</rptOwnerCik>
            <rptOwnerName>BERNSTEIN KENNETH F</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>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President and CEO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares of Beneficial Interest - $.001 Par Value</value>
            </securityTitle>
            <transactionDate>
                <value>2012-02-17</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>75000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>21.99</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>470471</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">These shares were sold in 11 separate sales transactions at a weighted average sales price of $21.99181818.  The actual price at which these shares were sold range from $21.94 to $22.06 per share.  Mr. Bernstein will provide, upon request by the Securities and Exchange Commission staff, the issuer, or a security holder of the issuer, full detailed information regarding the number of shares sold at each separate price.</footnote>
        <footnote id="F2">In part, these shares were sold to reimburse Mr. Bernstein for the income taxes due in connection with the conversion on February 14th of LTIP Units ultimately into common shares of Acadia Realty Trust.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Kenneth F. Bernstein</signatureName>
        <signatureDate>2012-02-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
