The former Parma and Juventus boss has signed a three-year deal at Stamford Bridge.
Ancelotti left his job as AC Milan coach on Sunday, with one year left on his contract with the club.
A statement on the club’s official website read: “Chelsea Football Club is delighted to announce that Carlo Ancelotti has agreed to become our new manager.
“He has signed a three-year contract and will start on July 1, 2009.
“Carlo was the outstanding candidate for the job. He has proved over a long period his ability to build teams that challenged for, and have been successful in, major domestic and European competitions.
“He also had a highly successful playing career in those competitions and therefore brings unparalleled all round experience to the job.
“We are sure everybody at Chelsea will give him a warm welcome and we are all looking forward to working with him.”
