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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-12-07</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001647509</issuerCik>
        <issuerName>Forest City Realty Trust, Inc.</issuerName>
        <issuerTradingSymbol>FCEA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001706021</rptOwnerCik>
            <rptOwnerName>Patel Ketan K</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>50 PUBLIC SQUARE, SUITE 1360</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CLEVELAND</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>44113</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP, Sec and GC</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-12-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F3"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>12446</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>2018 Performance Shares</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2018-12-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F4"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>4148</value>
                    <footnoteId id="F4"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2020-12-31</value>
            </exerciseDate>
            <expirationDate>
                <value>1988-08-08</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>6223</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">2018 Restricted Stock Grant - 25% vest on 3/24/2019;  25% vest on 3/24/2020; and 50% vest on 3/24/2021.</footnote>
        <footnote id="F2">Performance Shares Award -  granted 3/20/2018 - performance period is from January 1, 2018 to December 31, 2020.  Awards will be available to the grantee at the end of the performance period provided that certain performance criteria are met. The actual number of shares earned could range from 0 to 200% of the number of Performance Shares granted.  Fair market value on date of grant is  $20.89 per share.  There is no fixed expiration date.</footnote>
        <footnote id="F3">Pursuant to a Merger Agreement dated 7/30/2018, among issuer, Antlia Holdings, LLC and Antlia Merger Sub Inc. (the &quot;Merger Agreement&quot;), on December 7, 2018,  at the effective time of the Merger (the &quot;Effective Time&quot;), pursuant to the terms of the Merger Agreement, the unvested restricted shares outstanding immediately prior to the Effective Time automatically vested and entitled the holder to receive a cash payment of $25.35 per share (the &quot;Merger Consideration&quot;), without interest and less any applicable tax withholdings.</footnote>
        <footnote id="F4">At the Effective Time of the Merger, a pro-rated amount of 1/3 (at 200% of target) of the Performance Share Award granted in 2018, automatically vested and entitled the holder to receive a cash payment of the Merger Consideration (as defined above) per vested and awarded Performance Share, without interest and less any applicable tax withholding.  The target amount awarded was based on the Issuer's actual performance through the Effective Time, as reasonably determined in good faith by the compensation committee of the Board of Directors.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>J. Matthew Shady, Attoney-In-Fact for Ketan K. Patel</signatureName>
        <signatureDate>2018-12-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
