The school on Tuesday announced the departures of Martin, defensive line coach Kenechi Udeze and defensive backs coach Ronnie Bradford. USC also said quarterbacks coach Bryan Ellis has left the staff to pursue another opportunity. USC fired offensive line coach Neil Callaway in October.
Helton took away play-calling responsibility from Martin, the former Tennessee quarterback who led the Vols to the national championship after the 1998 season. The Trojans were 83rd in the FBS in total offense, 91st in scoring and 108th in rushing.
USC lost five of its final six games, capped by back-to-back defeats by archrivals UCLA and Notre Dame. The Trojans will not be going to a bowl game in a non-probation season for the first time since 2000.
Athletic director Lynn Swann announced Sunday that he is keeping Helton as coach based on previous success and Swann’s desire for continuity.
Helton is 32-17 in his first head coaching job, which began midway through the 2015 season. USC won the Rose Bowl two years ago to cap a nine-game winning streak, and it won the Pac-12 title last season.