Looney had the operation to repair a torn labrum on Thursday. He will begin rehabilitation immediately and will not be able to resume basketball activity for four to six months.
Warriors general manager Bob Myers said it was best to address the injury now and that the team is confident Looney will have a full recovery.
Looney was the 30th pick in the June draft. In one season at UCLA he averaged 11.6 points and 9.2 rebounds.