"Ed is an expert when it comes to the defensive line," LSU Coach Les Miles said in a statement on the school's website. "He's going to bring tremendous enthusiasm and energy to our program. Ed has done a great job at every coaching stop he's made and we are really excited to have him join the program."
Orgeron, who lives in Louisiana, coached defensive line and was the recruiting coordinator at USC under Pete Carroll and Lane Kiffin.
Orgeron was named interim coach after Kiffin was fired five games into the 2013 season.
Orgeron revitalized the Trojans but abruptly left the program after Athletic Director Pat Haden hired Steve Sarkisian as Kiffin's permanent replacement.
Orgeron did not coach this season. In November, he told The Times' Bill Plaschke that he would be open to returning to USC, but Sarkisian never indicated that was a possibility.