Riley's appointment was announced Thursday by new coach Jonathan Smith, who played one season (1998) under Riley and later was a graduate assistant (2003) on Riley's staff.
Riley served two stints as Oregon State's coach -- from 1997-98 and 2003-14 -- and is the school's all-time winningest coach. Riley had a 93-80 record with the Beavers before spending the past three seasons at Nebraska, where he was fired with a 19-19 record.
"Current and former players thriving in the NFL and in life are proof of Coach Riley's tremendous ability to recruit outstanding young men," Smith said on the school's website. "He understands what it takes to win in this (Pac-12) conference, and how to evaluate and develop student-athletes. There is no one better to have represent OSU in the homes of recruits as we build this program."
In between his two Oregon State head-coaching stints, Riley spent three seasons with the NFL's San Diego Chargers, going 14-34 before being fired.
Smith also announced the additions of Brian Lindgren (offensive coordinator), Jim Michakczik (run game coordinator/offensive line coach) and Jake Cookus (special teams coordinator).