Toronto FC honoured Kevin Harmse's request Wednesday, trading the Canadian international to Chivas USA in return for allocation money.
Harmse, a 24-year-old midfielder, started in eight of 12 matches this season, his second with Toronto.
"Kevin requested a move back to the U.S.," Toronto FC general manager Mo Johnston said in a statement.
"We tried very hard to hang on to him. But this move is what's best for Kevin right now."
Harmse, from Vancouver, has one goal in 30 MLS matches with the Los Angeles Galaxy and Toronto FC, who acquired him for a fourth-round draft pick on Feb. 28, 2008.
He played for the Vancouver Whitecaps of the USL in 2004 and 2005.