Mitchell played all six games as a true freshman during the COVID-19-shortened 2020 season, totaling seven tackles.[6] He then started all 13 games in 2021 at cornerback, totaling 34 tackles, eight pass breakups, one forced fumble and one fumble recovery, along with a sack.[7]
Mitchell remained a full-time starter in 2022, starting all 14 games while posting 41 tackles, 25 passes defended (which led the country), five interceptions, and 3.5 TFLs.[8][9] He was named the national defensive player of the week after recording four interceptions and two pick sixes in a win over Northern Illinois; his four interceptions tied the school record.[4][10] He was selected first-team All-Mid-American Conference (MAC) and was a second-team All-America honoree by the Walter Camp Foundation.[4][11]
In 13 games during the 2023 season, Mitchell compiled 41 total tackles, 18 passes defended, and one interception.[12] He was named a semifinalist for the Chuck Bednarik Award, being Toledo's first player to earn the honor, and was chosen a first-team All-American, being the second back-to-back All-American in school history.[13] He also was invited to the 2024 Senior Bowl.[14]