Johnson grew up in Chattanooga, Tennessee and attended Notre Dame High School.
After serving as a reserve outside linebacker as a freshman, he became a starting edge rusher going into his sophomore year and was named second-team All-American Athletic Conference (AAC) after leading the team with 10.5 sacks, 16 tackles for loss and four forced fumbles.
[2][3] Johnson was named second-team All-AAC for a second straight season after recording four sacks and 8.5 tackles for loss with four passes broken up as a junior.
[7] Johnson was selected in the seventh round with the 234th overall pick of the 2021 NFL draft by the Philadelphia Eagles.
[11] On September 17, 2024, Johnson was claimed off waivers by the New York Giants.