Malik Dorton helped lead Bellflower St. John Bosco High to an undefeated season.
The defensive end/linebacker signed a national letter of intent on Wednesday with USC, the school announced.
Dorton is 6 feet 2 and 250 pounds.
USC is replacing two starters from its defensive front.
Linebacker Devon Kennard completed his eligibility and end George Uko declared for the NFL draft.