Texas Tech
Shortly before the start of the 2013 season, Mayfield was named as the starting quarterback following a back injury of projected starter and former Lake Travis quarterback Michael Brewer.[6] Mayfield is believed to be the first walk-on true freshman quarterback to start a season opener at the quarterback position.[7]
In his first start against SMU, Mayfield passed for 413 yards and four touchdowns. His 43 completions of 60 attempts broke a school record held by Billy Joe Tolliver, and fell only four completions short of the NCAA Division I FBS single-game record for completions by a freshman.[8][9] For his performance, Mayfield was named Big 12 Conference Offensive Player of the Week – the first freshman Texas Tech quarterback to be named so since current Red Raider head coach Kliff Kingsbury in 1999.[10] The game featured the last four former Lake Travis quarterbacks combined on both teams: Garrett Gilbert, Michael Brewer, Collin Lagasse, and Mayfield.[11]
Following the Red Raiders' second victory over Stephen F. Austin, Mayfield's 780 season yards and seven touchdowns already exceeded the 755 yards and six touchdowns accrued by Texas Tech's last true freshman quarterback, Aaron Keesee, in 10 games.[12] After being affected by injury and losing the starting job to fellow true freshman Davis Webb, Mayfield finished the season with 2,315 yards on 218-of-340 completions with 12 touchdowns and 9 interceptions.
Mayfield was named one of 10 semifinalists for the Burlsworth Trophy in November; the award is given to the best player in Division I football who began his college career as a walk-on.[13]
Mayfield earned Big 12 Conference Freshman Offensive Player of the Year for the 2013 season. Mayfield announced that he would be leaving the program due to a 'miscommunication' with the coaching staff.[14][15]
Oklahoma
Mayfield enrolled at the University of Oklahoma in January 2014, but had not contacted the Sooner coaching staff. Mayfield further elaborated in an interview with ESPN that he sought to transfer due to scholarship issues and a perception that he had earned the starting position and that further competition was not "really fair".[14][16] The alleged scholarship issues were denied by Texas Tech coach Kliff Kingsbury.[17]
In February 2014, Oklahoma head coach Bob Stoops confirmed that Mayfield would be walking on for the Oklahoma Sooners. Mayfield was not eligible to play until the 2015 season, and lost a season of eligibility due to Big 12 Conference transfer rules following an unsuccessful appeal of his transfer restrictions.[18] On August 24, 2015, Mayfield was named the starting quarterback for the Sooners after winning an open quarterback competition against Trevor Knight. On September 6, 2015, Mayfield started against Akron. Mayfield totaled 388 yards through the air with 3 touchdowns on 23 completions in the 41–3 win.[19] In the second game of the 2015 season, Mayfield started at Tennessee at Neyland Stadium. The Sooners were ranked 19th at the time and the Volunteers were ranked 23rd. Mayfield started off very slow in the game, not even reaching midfield until the 13-minute mark of the 4th quarter. Oklahoma came back from a 17-point deficit to win the game in double overtime. Mayfield threw for 187 yards and three touchdowns on 19 completions while throwing two interceptions early in the game in the 31–24 2OT win.[20] In the third game of the season, Mayfield got the start against Tulsa. He had a career day throwing for 487 yards and four touchdowns, including 316 yards at half. Mayfield also ran for 85 yards and two touchdowns in the 52–38 win.[21][22]
Mayfield finished the year with 3,700 passing yards, 36 touchdowns, and seven interceptions. He finished fourth in the Heisman Trophy voting and helped lead Oklahoma to the College Football Playoff semifinal (2015 Orange Bowl). However, they lost to Clemson by a score of 37–17.[23]
It was announced on December 5, 2016 that Mayfield and his top receiving target, Dede Westbrook, would be finalists for the 2016 Heisman Trophy. It was also announced that they would play in the 2017 Sugar Bowl. Mayfield ended up finishing third in the Heisman voting.[24]
In the 2017 Sugar Bowl, Mayfield helped lead the Sooners to a 35–19 victory over Auburn. He finished the bowl game 19-for-28 with 296 passing yards and two touchdowns.[25]
On November 4, 2017, Mayfield threw for a career-high 598 yards against in-state rival Oklahoma State. Mayfield finished 24-for-36 with five passing touchdowns and Oklahoma won the game by a score of 62–52. Mayfield completed his career 3-0 as the starting Oklahoma quarterback in the Bedlam Series.