Born in New York City, Johnson grew up in a rough neighborhood in Brooklyn. As a teenager, his parents sent him to live with an aunt in Chicago where he had a better chance to thrive. He played football and wrestled at St. Joseph High School in Westchester, Illinois, where he was a three-year starter as a defensive tackle and offensive lineman and was named first-team All-area. However, in the middle of his junior year, due to a coaching change and a losing season, Johnson transferred to Montini Catholic High School for his senior season, and in his only campaign at Montini, Johnson was named team captain and earned first team All-state, All-conference and All-area honors as well as prep All-America recognition after helping the Broncos post 12-2 a record while winning the state championship, finishing with a 70-45 victory over Joliet Catholic. He recorded 80 tackles, including five tackles for loss, three sacks and nine pressures. During his time at St. Joseph, Johnson also earned two letters as a heavyweight wrestler. Regarded as a four-star recruit by Rivals.com, Johnson received scholarship offers from half of the Big Ten. It was Iowa coach Kirk Ferentz who convinced him to play for the Hawkeyes after he sent a personal letter that made an impression on Johnson. He took a few visits to Iowa City and decided to sign with the Hawkeyes. Shortly after Signing Day, Johnson decommitted to take a closer look at Michigan State one more time, but ended up committing back to Iowa.
College career
Johnson played at the University of Iowa from 2012 to 2016. Johnson had to wait a while before getting significant playing time due to Iowa's depth in the interior defensive line. He redshirted in 2012, and played in seven games as a reserve defensive tackle the following season, and then had 11 tackles, 2.5 for loss, as a backup in 2014. Given the starting role as a junior in 2015, Johnson garnered honorable mention All-Big Ten honors. Johnson stepped up his game in 2016, being named first-team All-Conference after leading his team with 10 tackles for loss and 7.5 sacks. In Iowa's biggest game in 2016 against No. 3 Michigan, Johnson was one of the biggest reasons the Hawkeyes won 14-13, as he led the team with 9 tackles, 2 tackles for loss, 1 sack and a safety in the second quarter. According to Pro Football Focus, Johnson ranked sixth among defensive tackles in pass rush productivity with 43 combined pressures in 330 snaps. During his five-year career with the Hawkeyes, Johnson posted 113 tackles, 18.5 of them for loss and 12.5 sacks.
Statistics
Professional career
Johnson was drafted by the Minnesota Vikings in the fourth round with the 109th overall selection in the 2017 NFL Draft.
