Yvan Muller will join Chevrolet's World Touring Car team next season
The 40-year-old Frenchman won the 2008 title for SEAT and finished runner-up to team-mate Gabriele Tarquini this season, but will join the RML Chevrolet team for 2010 alongside Rob Huff and Alain Menu.
"I am delighted to join Chevrolet for next season," said Muller. "After four successful and exciting years with SEAT I was looking for a new challenge, and Chevrolet was my first choice.
"I have known RML since my years in the BTCC and I have witnessed the impressive growth of Chevrolet in the WTCC. I am confident in the potential of the Cruze and I am sure that together with Alain, Rob and the entire Chevrolet team, we can achieve great things."
Muller won the 2003 British Touring Car title before leaving the series to join SEAT in the WTCC in 2006.
RML boss Ray Mallock added: "Yvan has been a respected competitor of RML since the mid-90s and stands as one of the touring car greats. Our signing of him confirms our commitment to winning this championship."