Peterson attended the University of Oklahoma, where he played for coach Bob Stoops' Oklahoma Sooners football team from 2004 to 2006. During his freshman season at Oklahoma, Peterson broke several NCAA freshman rushing records, rushing for 1,925 yards and leading the nation in carries with 339.[7] In the first nine games of the season, he rushed for more than 100-yards, which is a freshman record.[19] He rushed for 100 yards in the season opener against Bowling Green,[20] 117 yards against Houston, 183 yards against Oregon, 146 yards against Texas Tech, 225 yards against Texas, 130 yards against Kansas State, and 122 yards against Kansas.[19][21]
Against Oklahoma State on October 30, 2004, Peterson had an 80-yard touchdown run and rushed for 161 yards in the third quarter, finishing with a career-high 249 yards.[22] Despite dislocating his left shoulder in the first half, he managed to run for 101 yards and a touchdown on 29 carries, his ninth straight 100-yard game, against Texas A&M.[23] In the next game, he saw little action because of his shoulder injury and finished with 58 yards, which ended his streak of consecutive games with at least 100 yards rushing at 9.[24] In a game versus Baylor, Peterson ran for 240 yards, including three second-half touchdowns,[25] and set the NCAA record for most 100-yard games by a freshman with 11 against Colorado.[26] Oklahoma, who were one of the poorest rushing teams the year before, became one of the nation’s best.
Despite his record-breaking season, he finished second to USC quarterback Matt Leinart in the Heisman Trophy voting.[7] Among other honors, he was a finalist for the Doak Walker Award,[27] and the first Oklahoma freshman recognized as a First-Team Associated Press All-American.[7] Peterson contributed to a perfect regular season for the Oklahoma Sooners and participated in the 2005 BCS National Championship Game with a berth to the 2005 Orange Bowl against USC Trojans.[27] USC retooled their defense to stop Peterson and limited him to just 82 yards, as the Trojans defeated the Sooners, 55-19. USC later vacated the win due to NCAA infractions. After the season, he had surgery on his left shoulder to strengthen the muscles around the joint.[10]