Sarkisian previously confirmed that receivers coach Tee Martin would be retained.
"I'm fired up to have Johnny, Keith and Peter join the staff, as well as keeping Tee on board," Sarkisian said in a statement. "We're on the right path in putting together one of the best coaching staffs in America."
Sarkisian will not designate titles and responsibilities until he has completed his staff.
Sirmon, 36, played at Oregon and for the NFL's
Clay Helton, USC's offensive coordinator under