UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d)

OF THE SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported): May 5, 2015

Commission file number 001-11625

Pentair plc

(Exact name of Registrant as specified in its charter)

P.O. Box 471, Sharp Street, Walkden, Manchester, M28 8BU United Kingdom

(Address of principal executive offices, including Zip Code)

Registrant’s telephone number, including area code: +44-161-703-1885

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Pentair plc (the “Company”) held its 2015 annual general meeting of shareholders on May 5, 2015. There were 179,773,760 ordinary shares issued and outstanding at the close of business on March 6, 2015 and entitled to vote at the annual general meeting. A total of 157,387,601 ordinary shares (87.54%) were represented at the annual general meeting.

The items voted upon at the annual general meeting and the results of the vote on each proposal were as follows:

Proposal 1. — Re-Election of Eleven Director Nominees

To re-elect eleven director nominees for one-year terms expiring at the 2016 annual general meeting of shareholders. Each nominee for director was re-elected by a vote of the shareholders as follows:

Proposal 2. — Non-Binding Advisory Vote to Approve the Compensation of the Named Executive Officers

To approve, by non-binding advisory vote, the compensation of the Company’s named executive officers. The compensation of the Company’s named executive officers was approved, by non-binding advisory vote, by shareholders as follows:

Proposal 3. — Ratification, by Non-Binding Advisory Vote, of the Appointment of Deloitte & Touche LLP as the Independent Auditors of the Company and Authorization, by Binding Vote, of the Audit and Finance Committee to Set the Auditors’ Remuneration

To ratify, by non-binding advisory vote, the appointment of Deloitte & Touche LLP as the Company’s independent auditors for the year ending December 31, 2015 and to authorize, by binding vote, the Audit and Finance Committee of the Board of Directors to set the independent auditors’ remuneration. The proposal was approved by a vote of the shareholders as follows:

Proposal 4. — Authorize Holding the 2016 Annual General Meeting of Shareholders of the Company at a Location Outside of Ireland

To authorize holding the 2016 Annual General Meeting of Shareholders of the Company at a location outside of Ireland. The proposal was approved by a vote of the shareholders as follows:

Proposal 5. — Authorize the Price Range at Which the Company Can Reissue Shares It Holds as Treasury Shares Under Irish Law

To authorize the price range at which the Company can reissue shares it holds as treasury shares under Irish law. The proposal was approved by a vote of the shareholders as follows:

SIGNATURE

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, hereunto duly authorized, on May 5, 2015.