Meanwhile, the Trojans announced Monday that they have signed Westchester High guard Elijah Stewart, the Los Angeles City Section player of the year.
Wesley said the most important factor in his decision was "the winning culture at Gonzaga."
"They've been to the [
"That group of players they have returning, there's a lot of seasoned veterans and I'm excited to learn from those guys because they've had great college experiences. I'm excited to be around a group that knows how to win and can make a run at a national championship."
ESPN.com first reported Wesley's decision to transfer to Gonzaga.
The 6-foot-5 Wesley was USC's leading scorer last season. He averaged 17.8 points and 6.4 rebounds a game.
Wesley must complete summer school classes and graduate to be eligible immediately at Gonzaga.
The 6-5 Stewart, who averaged 19.2 points per game for Westchester last season, joins a 2014 recruiting class that also includes guard Jordan McLaughlin, center Jabari Craig, forward Malik Price-Martin and wing Malik Marquetti.