[4] Following his redshirt season, Johnson saw significant playing time in 2019 and totaled 58 tackles, two interceptions and four pass breakups.
[4] In 2020, he earned second-team all-conference honors after having 81 total tackles, two forced fumbles and leading the American Athletic Conference (AAC) with 60 solo stops.
[5][6] He started all 12 games in 2021 and had 104 tackles, earning second-team all-conference honors while ranking 12th nationally with 66 solo stops.
[4][7] Johnson returned for a final season in 2022 and had a conference-leading four interceptions that placed him 22nd nationally; he additionally posted 77 tackles, four pass breakups and two forced fumbles on his way to being named first-team All-AAC.
[8] After going unselected in the 2023 NFL draft, Johnson was signed by the Los Angeles Rams as an undrafted free agent.