In his eighth start on the desert track, Keselowski earned his 28th career Nationwide win on his 20th track.
Busch came up from a 37th-place start to finish second on his hometown track, but couldn't catch Keselowski's Penske Ford.
Keselowski lost three spots early after sliding through his pit box. He later lost power because of a faulty alternator, forcing him to turn off equipment.
He still navigated through traffic on the final laps in an exciting finish.