Detroit Lions Johnson was selected by the
Detroit Lions in the second round (43rd overall) of the 2018 NFL draft. He was the sixth running back to be selected that year. He made his NFL debut in the season opener against the
New York Jets on
Monday Night Football. In the 48–17 loss, he had five carries for 17 yards and three
receptions for 20 yards. In a 26–10
Sunday Night Football victory over the
New England Patriots in Week 3, Johnson rushed for 101 yards, becoming the first Lions' player since
Reggie Bush in 2013 to rush for more than 100 yards. The performance won him the starting role over
LeGarrette Blount, which he used to score his first NFL touchdown the following week against the
Dallas Cowboys though he was limited to just nine carries. He added 70 yards against the
Green Bay Packers before the Week 6 bye. In Week 7 against the
Miami Dolphins, Johnson rushed for 158 yards on 19 carries with an additional 21 yards on two catches in a 32–21 victory. Nearly half of his rushing yards came on a 71-yard carry early in the game. He was second-youngest Lions' player to reach 150 yards rushing by just three days to
Barry Sanders, and the first Lions' player of any age since
Jahvid Best in 2011. He expanded his role in the passing game with career bests of six receptions for 69 yards in Week 8, and after just 43 yards-from-scrimmage in Week 9, notched both a rushing and his first career receiving touchdown in Week 10 loss to the
Chicago Bears. In the Week 11 win over the
Carolina Panthers, Johnson had 87 yards and a rushing touchdown before spraining his left knee in the third quarter and missed the next four games. He was placed on
injured reserve on December 19, 2018. In Week 2 of the 2019 season against the
Los Angeles Chargers, Johnson rushed 12 times for 41 yards and caught two passes for 47 yards and a touchdown as the Lions won 13–10. In Week 4 against the
Kansas City Chiefs, Johnson rushed 26 times for 125 yards and caught two passes for 32 yards in the 34–30 loss. He was placed on injured reserve on October 22, 2019, after undergoing knee surgery. He was designated for return from injured reserve on December 4, 2019, and began practicing with the team again. He was activated on December 21, 2019, prior to Week 16. Overall, in the 2019 season, Johnson finished with 403 rushing yards and three rushing touchdowns to go along with 10 receptions for 127 receiving yards and one receiving touchdown. On May 6, 2021, Johnson was waived by the Lions.
Philadelphia Eagles (first stint) On May 7, 2021, Johnson was claimed off waivers by the
Philadelphia Eagles. On August 17, 2021, he was waived by the Eagles with an injury designation and placed on injured reserve. He was released on August 26.
San Francisco 49ers On September 14, 2021, Johnson was signed to the
practice squad of the
San Francisco 49ers. He was released on October 5.
Philadelphia Eagles (second stint) Following
Miles Sanders suffering a broken bone in his hand and
Jordan Howard suffering a stinger, Johnson was signed to the Eagles practice squad on December 28. He was released on January 10, 2022. ==Career statistics==