Busch dominated most of the late stages of the race but trailed Hamlin and Logano coming into the last lap. Hamlin and Logano made contact and crashed in turn 3, giving Busch the opening he needed.
He slipped by to corral the win for Joe Gibbs Racing -- its first Sprint Cup Series victory at the 2-mile Fontana, Calif., track.
Hamlin was hospitalized after the crash, and was reported awake and alert.
Logano, who ended up in sixth, got into a fight with fellow driver Tony Stewart on pit road after the race. Stewart was upset that Logano blocked him during a late-race restart.