Johnson was born on November 5, 1999.[1] He and his twin brother Kendell grew up playing on the same youth sports teams, attending the same schools and ultimately playing for the same college football team.[2][3] He attended Edna Karr High School and helped them win back-to-back state championships in 2016 and 2017.[4] He committed to play college football for the Memphis Tigers, redshirting as a true freshman.[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.[6] He finished his collegiate career with 320 tackles, 24 pass breakups and 10 interceptions.[8]