Wicky, 31, played for clubs in Germany, Spain and Switzerland and earned 70 Swiss caps before moving to MLS. He played in the 2004 European Championship and 2006 World Cup. But an ankle injury limited him to one start and four appearances as a sub for Chivas USA in 2008.
"Raphael is a talented player with great experience and a good soccer brain," said Chivas USA coach Preki. "Last year was tough for him with his injury, but we are happy to have him back. We are confident he can continue to help Chivas USA in 2009."