Willis Towers Watson PLC is replacing almost half of its board including the chairman, the insurance broker’s latest effort to remake itself following the collapse of a merger with a major rival.

Following talks with activist investor Elliott Management Corp., Willis Towers is replacing four of its nonexecutive directors, including Chairman Victor Ganzi, with four new members. The insurance brokerage giant’s board is composed of eight nonexecutive directors and its chief executive.

The...

Willis Towers Watson PLC is replacing almost half of its board including the chairman, the insurance broker’s latest effort to remake itself following the collapse of a merger with a major rival.

Following talks with activist investor Elliott Management Corp., Willis Towers is replacing four of its nonexecutive directors, including Chairman Victor Ganzi, with four new members. The insurance brokerage giant’s board is composed of eight nonexecutive directors and its chief executive.

The Wall Street Journal previously reported the planned changes.

Mr. Ganzi has been on Willis Towers’ board since 2016, and served as chairman since 2019. He will step down from his current role at the company’s annual meeting next year, along with two other unidentified board members. Jaymin Patel, another board member, will leave at the beginning of January, Willis Towers said in a release.

Wills Towers Watson plans to replace its chairman, Victor Ganzi.

Photo: John Barrett/ZUMA Press

The four incoming directors include insurance industry veterans Inga Beale, a former chief executive of Lloyd’s of London, and Michael Hammond, a retired executive who most recently worked at Lockton, a Kansas City-based insurance broker. Also joining the board are Fumbi Chima, currently an executive at Boeing Employees’ Credit Union, and Michelle Swanback, an executive at Western Union Co.

Mses. Beale and Swanback and Mr. Hammond will join in January, while Ms. Chima will join in April.

Willis Towers is also setting up a new four member board committee focused on its turnaround effort. They include three of the new directors and current board member Paul Thomas.

Elliott, which Willis Towers’ describes as one of its largest shareholders, supports the planned board changes.

With a market value of close to $30 billion, Willis Towers is among the world’s largest firms that help companies buy insurance and advise them on risk management. In March 2020 it agreed to a $30 billion merger with rival Aon

PLC to generate cost savings and boost revenue. Antitrust opposition from the Justice Department prompted the companies to scrap the deal in July.

In September, The Wall Street Journal reported that activist investors including Elliot and Starboard Value LP had taken stakes in Willis Towers. The presence of those shareholders underscored the pressure on Willis Towers as a stand-alone company.

In addition to the board changes, the company said in August that longtime company insider Carl Hess would take over as chief executive in January and join the board at that time.

Willis Towers’ turnaround plan is focused on buying back stock, cutting costs and boosting revenue. The company has said it aims to buy back more than $4 billion worth of stock by the end of next year. Its shares are down 15% from their high in May.

The Ireland-based, U.S.-listed company is set to earn as much as $4 billion from a deal in August to sell its reinsurance business to

Arthur J. Gallagher & Co.

Willis Towers is also aiming to slash costs by $300 million over the next three years and boost revenue to more than $10 billion by the end of 2024, from $9.35 billion in 2020.

Write to Ben Dummett at ben.dummett@wsj.com