LONDON—Willis Group Holdings P.L.C. on Thursday extended the contract of Chairman and CEO Joseph J. Plumeri until July 7, 2013.

Mr. Plumeri’s previous agreement was set to expire in April 2011. The brokerage’s board of directors’ decision to extend Mr. Plumeri’s contract was due to Willis’ progress despite a soft market and economic downturn, the company said in a statement.

Mr. Plumeri joined Willis in 2000.