UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 6-K

REPORT OF FOREIGN PRIVATE ISSUER PURSUANT

TO RULE 13a-16 OR 15d-16 UNDER THE

SECURITIES EXCHANGE ACT OF 1934

For the month of September 2014.

Commission File Number: 001-35265

CSR plc

(Translation of registrant’s name into English)

Churchill House

Cambridge Business Park

Cowley Road

Cambridge CB4 0WZ

United Kingdom

Tel: +44 (0) 1223 692000

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F  x             Form 40-F  ¨

Indicate by checkmark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(l):  ¨

Indicate by checkmark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):  ¨

Indicate by check mark whether the registrant by furnishing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes  ¨             No  x

If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b): Not Applicable

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

NOT FOR RELEASE, PUBLICATION OR DISTRIBUTION IN ANY JURISDICTION WHERE TO DO SO WOULD CONSTITUTE A VIOLATION OF THE RELEVANT LAWS OF SUCH JURISDICTION

THIS DOES NOT CONSTITUTE AN ANNOUNCEMENT OF A FIRM INTENTION TO MAKE AN OFFER UNDER RULE 2.7 OF THE CITY CODE ON TAKEOVERS AND MERGERS (THE “CODE”). THERE CAN BE NO CERTAINTY THAT ANY FIRM OFFER WILL BE MADE

25 September 2014

Statement by CSR plc regarding extension to deadline

On 28 August 2014, CSR plc (“CSR” or the “Company”) announced that, in accordance with Rule 2.6(a) of the Code, Microchip Technology Incorporated (“Microchip”) is required, by not later than 5.00pm on 25 September 2014, to either announce a firm intention to make an offer for CSR in accordance with Rule 2.7 of the Code or announce that it does not intend to make an offer, in which case the announcement will be treated as a statement to which Rule 2.8 of the Code applies.

At the request of the board of the Company, the Panel has consented to an extension of this deadline until 5.00pm on 15 October 2014 to enable the parties to conclude their ongoing discussions. By this time Microchip must either announce a firm intention to make an offer for CSR or announce that they do not intend to make an offer, in which case the announcement will be treated as a statement to which Rule 2.8 of the Code applies. This deadline will only be extended with the consent of the Panel in accordance with Rule 2.6(c) of the Code.

There can be no certainty that an offer will be made nor as to the terms on which any offer might be made.

A copy of this announcement will be available on CSR’s website at www.CSR.com.

Enquiries:

CSR: Will Gardiner, Chief Financial Officer +44 (0) 1223 692 000

FTI Consulting: Charlie Palmer +44 (0) 20 3727 1000

J.P. Morgan Cazenove

Rupert Sadler / Madhu Namburi +1 212 270 6000

Dwayne Lysaght / Jonathan Wilcox / James Robinson +44 (0) 20 7777 2000

Goldman Sachs International

Pawan Tewari / Tammy Kiely +1 415 393 7500

Mark Sorrell / Nick Harper +44 (0) 20 7774 1000

Further Information

J.P. Morgan Limited, which conducts its UK investment banking businesses as J.P. Morgan Cazenove (“J.P. Morgan Cazenove”), is authorised and regulated in the United Kingdom by the Financial Conduct Authority. J.P. Morgan Cazenove is acting as financial adviser exclusively for CSR and no one else in connection with the matters set out in this announcement and will not regard any other person as its client in relation to the matters in this announcement and will not be responsible to anyone other than CSR for providing the protections afforded to clients of J.P. Morgan Cazenove, nor for providing advice in relation to any matter referred to herein.

Goldman Sachs International (“Goldman Sachs”), which is authorised by the Prudential Regulation Authority and regulated by the Financial Conduct Authority and the Prudential Regulation Authority in the United Kingdom, is acting for CSR and no-one else in connection with the matters set out in this announcement and will not be responsible to anyone other than CSR for providing the protections afforded to clients of Goldman Sachs nor for providing advice in relation to the matters in this announcement. Neither Goldman Sachs nor any of its subsidiaries, branches or affiliates owes or accepts any duty, liability or responsibility whatsoever (whether direct or indirect, whether in contract, in tort, under statute or otherwise) to any person who is not a client of Goldman Sachs in connection with this announcement, any statement contained herein or otherwise.

Dealing Disclosure Requirements

Under Rule 8.3(a) of the Code, any person who is interested in 1% or more of any class of relevant securities of an offeree company or of any securities exchange offeror (being any offeror other than an offeror in respect of which it has been announced that its offer is, or is likely to be, solely in cash) must make an Opening Position Disclosure following the commencement of the offer period and, if later, following the announcement in which any securities exchange offeror is first identified. An Opening Position Disclosure must contain details of the person’s interests and short positions in, and rights to subscribe for, any relevant securities of each of (i) the offeree company and (ii) any securities exchange offeror(s). An Opening Position Disclosure by a person to whom Rule 8.3(a) applies must be made by no later than 3.30 pm (London time) on the 10th business day following the commencement of the offer period and, if appropriate, by no later than 3.30 pm (London time) on the 10th business day following the announcement in which any securities exchange offeror is first identified. Relevant persons who deal in the relevant securities of the offeree company or of a securities exchange offeror prior to the deadline for making an Opening Position Disclosure must instead make a Dealing Disclosure.

Under Rule 8.3(b) of the Code, any person who is, or becomes, interested in 1% or more of any class of relevant securities of the offeree company or of any securities exchange offeror must make a Dealing Disclosure if the person deals in any relevant securities of the offeree company or of any securities exchange offeror. A Dealing Disclosure must contain details of the dealing concerned and of the person’s interests and short positions in, and rights to subscribe for, any relevant securities of each of (i) the offeree company and (ii) any securities exchange offeror, save to the extent that these details have previously been disclosed under Rule 8. A Dealing Disclosure by a person to whom Rule 8.3(b) applies must be made by no later than 3.30 pm (London time) on the business day following the date of the relevant dealing.

If two or more persons act together pursuant to an agreement or understanding, whether formal or informal, to acquire or control an interest in relevant securities of an offeree company or a securities exchange offeror, they will be deemed to be a single person for the purpose of Rule 8.3.

Opening Position Disclosures must also be made by the offeree company and by any offeror and Dealing Disclosures must also be made by the offeree company, by any offeror and by any persons acting in concert with any of them (see Rules 8.1, 8.2 and 8.4).

Details of the offeree and offeror companies in respect of whose relevant securities Opening Position Disclosures and Dealing Disclosures must be made can be found in the Disclosure Table on the Takeover Panel’s website at www.thetakeoverpanel.org.uk, including details of the number of relevant securities in issue, when the offer period commenced and when any offeror was first identified. You should contact the Panel’s Market Surveillance Unit on +44 (0)20 7638 0129 if you are in any doubt as to whether you are required to make an Opening Position Disclosure or a Dealing Disclosure.

NOT FOR RELEASE, PUBLICATION OR DISTRIBUTION IN ANY JURISDICTION WHERE TO DO SO WOULD CONSTITUTE A VIOLATION OF THE RELEVANT LAWS OF SUCH JURISDICTION

29 September 2014

CSR plc (“CSR”)

Disclosure of Issued Shares Pursuant to Rule 2.10

In accordance with Rule 2.10 of the City Code on Takeovers and Mergers (the “Code”), CSR confirms that, as at the date of this announcement, it has 185,019,776 ordinary shares of 0.1 pence admitted to trading on the main market of the London Stock Exchange under the International Securities Identification Number (“ISIN”) GB0034147388. 19,907,361 shares are held in Treasury.

CSR has an American Depositary Receipts (“ADR”) programme for which JPMorgan Chase acts as Depositary. 1 ADR represents 4 ordinary shares of CSR. The ADRs trade on the NASDAQ Global Select Market of NASDAQ Stock Market LLC. The trading symbol for these securities is CSRE and the ISIN is US12640Y2054.

The total number of shares attracting voting rights in CSR is therefore 165,112,415. This figure may be used by shareholders to determine the percentage of issued share capital they hold in CSR.

Enquiries:

CSR: Will Gardiner, Chief Financial Officer +44 (0) 1223 692 000

FTI Consulting: Charlie Palmer +44 (0) 20 3727 1000