Wallace did not see any action during his freshman and sophomore years at Alabama. He earned a walk-on scholarship before his junior year in 2016. In 6 games, Wallace totaled 11 tackles. During his senior year, Wallace started in 14 games. He was a starter during the 2018 College Football Playoff National Championship game, where Alabama won in overtime over Georgia, 26-23. Wallace totaled 48 tackles and caught 3 interceptions in his senior year.