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

    <schemaVersion>X0609</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-03-20</periodOfReport>

    <issuer>
        <issuerCik>0000719955</issuerCik>
        <issuerName>WILLIAMS SONOMA INC</issuerName>
        <issuerTradingSymbol>WSM</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001539835</rptOwnerCik>
            <rptOwnerName>King David Randolph</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>3250 VAN NESS AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94109</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>EVP GENERAL COUNSEL</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

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                <value>Common Stock</value>
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            <transactionDate>
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                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>23376</value>
                </transactionShares>
                <transactionPricePerShare>
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                </transactionPricePerShare>
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                </transactionAcquiredDisposedCode>
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            </transactionCoding>
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                </transactionPricePerShare>
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                <transactionPricePerShare>
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                </transactionAcquiredDisposedCode>
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                </sharesOwnedFollowingTransaction>
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                    <footnoteId id="F1"/>
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                </transactionShares>
                <transactionPricePerShare>
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                </transactionPricePerShare>
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                </sharesOwnedFollowingTransaction>
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        </nonDerivativeTransaction>
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                </transactionPricePerShare>
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                </transactionAcquiredDisposedCode>
            </transactionAmounts>
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                <sharesOwnedFollowingTransaction>
                    <value>114832</value>
                </sharesOwnedFollowingTransaction>
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                </directOrIndirectOwnership>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
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            </transactionDate>
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                <transactionShares>
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                </transactionShares>
                <transactionPricePerShare>
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                </transactionPricePerShare>
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                </transactionAcquiredDisposedCode>
            </transactionAmounts>
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                <sharesOwnedFollowingTransaction>
                    <value>116030</value>
                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
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                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-03-22</value>
            </transactionDate>
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                <transactionFormType>4</transactionFormType>
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            <transactionTimeliness></transactionTimeliness>
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                </transactionPricePerShare>
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                <sharesOwnedFollowingTransaction>
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                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
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        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
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                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
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                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Managed Account</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
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            <conversionOrExercisePrice>
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            <transactionDate>
                <value>2026-03-20</value>
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                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
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                </transactionShares>
                <transactionPricePerShare>
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                <transactionAcquiredDisposedCode>
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            </transactionAmounts>
            <exerciseDate>
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            </exerciseDate>
            <expirationDate>
                <footnoteId id="F5"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
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                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>23376</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                </sharesOwnedFollowingTransaction>
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        </derivativeTransaction>
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            </securityTitle>
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            <transactionDate>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness></transactionTimeliness>
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                    <value>23376</value>
                </transactionShares>
                <transactionPricePerShare>
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                <transactionAcquiredDisposedCode>
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            <expirationDate>
                <footnoteId id="F5"/>
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                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>23376</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness></transactionTimeliness>
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                <transactionShares>
                    <value>4264</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
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                </underlyingSecurityShares>
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        <derivativeTransaction>
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                <value>Restricted Stock Units</value>
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            <transactionDate>
                <value>2026-03-21</value>
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                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3778</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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            </underlyingSecurity>
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                    <value>3780</value>
                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
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                </directOrIndirectOwnership>
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        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
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                <transactionCode>M</transactionCode>
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                <transactionPricePerShare>
                    <value>0</value>
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            <exerciseDate>
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            <expirationDate>
                <footnoteId id="F5"/>
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                <underlyingSecurityTitle>
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                </underlyingSecurityTitle>
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                    <value>1198</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2396</value>
                </sharesOwnedFollowingTransaction>
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        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Represents the number of shares withheld upon vesting of restricted stock units to cover tax withholding obligations.</footnote>
        <footnote id="F2">Represents the number of shares held by the reporting person in the Williams-Sonoma, Inc. Stock Fund under the Williams-Sonoma, Inc. 401(k) Plan, based on a statement dated March 22, 2026.</footnote>
        <footnote id="F3">Each restricted stock unit represents a contingent right to receive one share of WSM common stock.</footnote>
        <footnote id="F4">Represents restricted stock units granted on March 21, 2023, which reflect the satisfaction of performance metrics. The restricted stock units were also subject to a continued service condition, which was satisfied on March 21, 2026.</footnote>
        <footnote id="F5">The restricted stock units are cancelled upon vesting and delivery of shares of WSM common stock.</footnote>
        <footnote id="F6">The restricted stock units vest in four equal installments on each anniversary of the grant date in 2023, 2024, 2025 and 2026.</footnote>
        <footnote id="F7">The restricted stock units vest in four equal installments on each anniversary of the grant date in 2024, 2025, 2026 and 2027.</footnote>
        <footnote id="F8">The restricted stock units vest in four equal installments on each anniversary of the grant date in 2025, 2026, 2027 and 2028.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ David R. King</signatureName>
        <signatureDate>2026-03-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
