Riley previously served as the head coach at the University of Oklahoma for five seasons from 2017 to 2021, where he won four consecutive Big 12 Championship Games.

[2] As a fifth-year head coach, he has produced over 28 draft picks including 5 first-rounders, but is 3–4 in end-of-season bowl games and 0–3 in the College Football Playoff.

Following his departure from Texas Tech after the firing of Leach, Riley went on to serve five seasons as offensive coordinator at East Carolina University[5] under Ruffin McNeill.

[12] On November 28, 2021, Riley was named the 30th head coach of the USC Trojans football program representing the University of Southern California, replacing Clay Helton.

"[13] The Los Angeles Times pointed out that Riley "still has an itch to scratch when it comes to winning at the highest level of the sport" and must feel he can "reach the summit more easily from USC.

"[14] Riley himself cited, in an interview given to SportsCenter two days later, the "history and tradition of one of the greatest college football programs of all time, the city, the Mecca of sports right here in Los Angeles" were what had lured him over to USC.

[22] His younger brother, Garrett Riley, currently serves as the offensive coordinator at Clemson University, and was previously the running backs coach at Appalachian State.