Johnson grew up in Cumberland, Maryland, and attended Fort Hill High School.

[8] For comparison, the fastest 40-yard dash time ran by any running back at the 2019 NFL Scouting Combine was 4.40 seconds by Justice Hill of the Oklahoma State Cowboys.

[9] At his pro day workout, Johnson was also able to do 27 repetitions of the bench press at 225 pounds, which would have ranked the highest among 2019 Combine running backs,[10] and was recorded jumping a 34-inch vertical.

[11] Johnson made his NFL debut in the Lions' regular season opener against the Arizona Cardinals and had a six-yard carry in the 27–27 tie.

[12] Johnson made his first career start in Week 10 against the Chicago Bears and had five carries for 16 rushing yards.

[16] In Week 13 against the Las Vegas Raiders, Johnson rushed 22 times for 104 yards and a touchdown during the 31–28 loss.

He finished the regular season with 194 all-purpose yards and a receiving touchdown, which he scored in Week 11 against the New York Jets.

[26] In the Bills' two postseason games following the 2023 season, including a victory against the Pittsburgh Steelers in the wild card round and a loss to the Kansas City Chiefs in the divisional round, Johnson rushed 15 times for 66 yards, which put him over 1,000 total rushing yards for his career.