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): July 23, 2014

Willis Group Holdings Public Limited Company

(Exact name of registrant as specified in its charter)

c/o Willis Group Limited, 51 Lime Street, London, EC3M 7DQ, England and Wales

(Address, including Zip Code, of Principal Executive Offices)

Registrant’s telephone number, including area code: (011) 44-20-3124-6000

Not Applicable

(Former name or former address, if changed since last report)

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:

On July 23, 2014, Willis Group Holdings Public Limited Company (“Company”) held the 2014 Annual General Meeting of Shareholders (the “2014 AGM”) at the Four Seasons Hotel in Dublin, Ireland. Proxies for the 2014 AGM were solicited pursuant to Regulation 14A under the Securities Exchange Act of 1934, as amended, and there was no solicitation in opposition to the Company’s solicitation.

A total of 160,662,388 ordinary shares (representing approximately 89.96% of 178,583,008 ordinary shares outstanding and entitled to vote as of May 30, 2014, the record date for the 2014 AGM) were present in person or by proxy, constituted a quorum for the transaction of business, and were voted at the 2014 AGM.

At the 2014 AGM, shareholders elected Mr. Dominic Casserley, Ms. Anna C. Catalano, Sir Roy Gardner, Sir Jeremy Hanley, Ms. Robyn S. Kravit, Ms. Wendy E. Lane, Mr. Francisco Luzón, Mr. James F. McCann, Mr. Jaymin Patel, Mr. Douglas B. Roberts, Dr. Michael J. Somers and Mr. Jeffrey W. Ubben to serve as directors until the next annual general meeting of shareholders or until his/her successor is elected and qualified.

The table below sets out the number of votes cast for and against each director, as well as abstentions and broker non-votes:

The shareholders also ratified the reappointment of Deloitte LLP as the Company’s independent auditors until the close of the next annual general meeting of shareholders, and authorized the Board of Directors, acting through the Audit Committee, to fix the independent auditor’s remuneration. Of the shares voted, 160,365,530 voted in favor, 161,142 voted against and 135,716 abstained.

The shareholders approved, on an advisory (non-binding) basis, the executive compensation of the Company’s named executive officers as disclosed in the Company’s proxy statement for the 2014 AGM in accordance with the Security and Exchange Commission’s rules, including the “Compensation Discussion and Analysis,” the “Summary Compensation” table and related tables and disclosure. Of the shares voted, 140,576,861 voted in favor, 13,894,429 voted against, 260,009 abstained and there were 5,931,089 broker non-votes.

The shareholders approved an amendment to the Willis Group Holdings Public Limited Company 2012 Equity Incentive Plan to increase the number of shares authorized for issuance under the 2012 Plan. Of the shares voted, 135,204,733 voted in favor, 19,334,840 voted against, 191,726 abstained and there were 5,931,089 broker non-votes.

The shareholders approved renewing the directors’ authority to issue shares under Irish law. Of the shares voted, 122,298,028 voted in favor, 32,076,244 voted against, 357,027 abstained and there were 5,931,089 broker non-votes.

Although the Company received support from 74.9% of the shares voted, the proposal to renew the directors’ authority to opt-out of statutory pre-emption rights under Irish law did not pass because it required support from at least 75% of the shares voted at the meeting. Of the shares voted, 115,540,104 voted in favor, 38,789,007 voted against, 402,188 abstained and there were 5,931,089 broker non-votes.

The shareholders approved holding the 2015 Annual General Meeting of Shareholders of Willis Group Holdings Public Limited Company at such place outside Ireland as may be determined by the Board of Directors. Of the shares voted, 160,304,729 voted in favor, 18,285 voted against, 339,374 abstained.

SIGNATURES

Pursuant to the requirement 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.