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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2016-02-01</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001649338</issuerCik>
        <issuerName>Broadcom Ltd</issuerName>
        <issuerTradingSymbol>AVGO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001211588</rptOwnerCik>
            <rptOwnerName>TAN HOCK E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O AVAGO TECHNOLOGIES US INC.</rptOwnerStreet1>
            <rptOwnerStreet2>1320 RIDDER PARK DRIVE</rptOwnerStreet2>
            <rptOwnerCity>SAN JOSE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95131</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>Ordinary Shares, no par value</value>
            </securityTitle>
            <transactionDate>
                <value>2016-02-01</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>134979</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>134979</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option(Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>38.99</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2016-02-01</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1547916</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2020-09-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Ordinary Shares, no par value</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1547916</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                    <value>1547916</value>
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            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option(Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>35.45</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2016-02-01</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
                <transactionShares>
                    <value>131250</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <value>2020-03-11</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Ordinary Shares, no par value</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>131250</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>131250</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option(Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>32.39</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2016-02-01</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>200000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <value>2018-03-07</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Ordinary Shares, no par value</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>200000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>200000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option(Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>52.65</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2016-02-01</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>750000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F7"/>
            </exerciseDate>
            <expirationDate>
                <value>2021-01-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Ordinary Shares, no par value</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>750000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>750000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Includes 35,416 Restricted Stock Units.</footnote>
        <footnote id="F2">Acquired in connection with the transactions consummated on February 1, 2016 pursuant to the terms of an Agreement and Plan of Merger, dated as of May 28, 2015, by and among the Issuer, Avago Technologies Limited (&quot;Avago&quot;), Broadcom Corporation (&quot;Broadcom&quot;), Safari Cayman L.P., Avago Technologies Cayman Holdings Ltd., Avago Technologies Cayman Finance Limited, Buffalo CS Merger Sub, Inc. (&quot;CS Merger Sub&quot;) and Buffalo UT Merger Sub, Inc. (&quot;UT Merger Sub,&quot; and, together with CS Merger Sub, the &quot;Merger Subs&quot;), pursuant to which (a) the Issuer indirectly acquired Avago pursuant to the terms of a scheme of arrangement under Singapore law consummated in accordance with Section 210 of the Companies Act (Chapter 50) of Singapore, and (b) the Merger Subs merged with and into Broadcom, with Broadcom as the surviving corporation in such mergers (collectively, the &quot;Transactions&quot;). Continued in footnote (3).</footnote>
        <footnote id="F3">As a result of the Transactions, (x) both Avago and Broadcom became indirect subsidiaries of the Issuer, (y) all issued ordinary shares of Avago were exchanged on a one-for-one basis for newly issued Ordinary Shares of the Issuer, and (z) each outstanding share option or restricted share unit issued by Avago has been converted into an option to purchase Ordinary Shares of the Issuer or an Issuer restricted share unit, respectively, covering the same number of Ordinary Shares of the Issuer as the number of ordinary shares of Avago that were subject to such share option or restricted share unit immediately prior to the Transactions and, in the case of share options, at the same per share exercise price of the related share option of Avago immediately prior to the Transactions.</footnote>
        <footnote id="F4">Share price performance option (the &quot;2006 Option&quot;) granted pursuant to the Avago Technologies Limited 2009 Equity Incentive Award Plan (the &quot;Avago Plan&quot;). The 2006 Option is fully vested and the exercisability requirements for the 2006 Option have been met.</footnote>
        <footnote id="F5">Share price performance option (the &quot;2013 Option&quot;) granted pursuant to the Avago Plan. The 2013 Option vests over four years, with 25% vesting on each anniversary of the date of grant, such that the 2013 Option will be fully vested on March 12, 2017. The exercisability requirements for the 2013 Option have been met.</footnote>
        <footnote id="F6">The option is fully vested and exercisable.</footnote>
        <footnote id="F7">Share price performance option (the &quot;2014 Option&quot;) granted pursuant to the Avago Plan. The 2014 Option vests over four years, with 25% vesting on each anniversary of the date of grant, such that the 2014 Option will be fully vested on January 2, 2018, based on the Reporting Person's continued service to the Company. The exercisability requirements for the 2014 Option have been met.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Patricia H. McCall, Attorney-in-Fact for Hock E. Tan</signatureName>
        <signatureDate>2016-02-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
