Johnson played cornerback for his first four seasons with the Iowa State Cyclones and became a starter during his freshman year.[3] As a senior, he was named honorable mention All-Big 12 Conference after making 55 tackles with three tackles for loss, four passes broken up, and two forced fumbles.[4] Johnson used the extra year of eligibility granted to college athletes due to the COVID-19 pandemic and returned to Iowa State for a fifth season.[5] He moved to safety entering his final season.[6] Johnson was named second team All-Big 12 after finishing the year with 60 tackles, two interceptions, and four passes broken up.[7]
On August 11, 2023, Johnson made his NFL preseason debut with the Packers in a 36–19 victory against the Cincinnati Bengals. In that game he finished with five total tackles four of which were solo tackles. After three preseason games Johnson finished with nine total tackles five of which were solo tackles.
Johnson would not make his NFL regular season debut until week seven in a 17–19 loss against the Denver Broncos. He only played 15 snaps during the game, 11 of them being on special teams. He would not record a stat. Johnson would make his first career start in week 9 against the Los Angeles Rams, covering for injured safety Rudy Ford.[13] This turned out to be Johnson's "breakout game", as in the fourth quarter Rams quarterback Brett Rypien's pass intended for receiver Cooper Kupp was tipped by Packer's Jaire Alexander. This allowed Johnson to make a play on the ball and come down with the interception.[14] Johnson would finish the game with two pass deflections, one tackle, one interception and played every defensive snap as Green Bay went on to win 20–3.[15] Johnson's best game of the year however came in week 12 on Thanksgiving day in a 29–22 win over the NFC North rival Detroit Lions. He finished with eight total tackles and one pass deflection.[16]
Johnson remained on the Packers roster through the entire 2024 preseason, but was ultimately released by the team on cutdown day, August 27, 2024.[17]
New York Giants
After being cut by the Packers, Johnson was claimed off waivers by the New York Giants on August 28, 2024.[18]