<?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>0001438803</rptOwnerCik>
            <rptOwnerName>Guilmart Bruno</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>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></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>5132</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5132</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>37</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>20094</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2018-06-04</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Ordinary Shares, no par value</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>20094</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>20094</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Includes 2,566 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">The option vests over 3 years, with 33.333% vesting on each of the first three anniversaries of June 5, 2013, so that the option will be vested in full on June 5, 2016, subject to the Reporting Person's continuing service on each vesting date.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Patricia McCall, Attorney-in-Fact for Bruno Guilmart</signatureName>
        <signatureDate>2016-02-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
