He played college football for the Wake Forest Demon Deacons and was selected by the Houston Texans in the first round of the 2015 NFL draft.

Johnson attended River Hill High School in Clarksville, Maryland, where he played both cornerback and running back.

Representatives and scouts from 22 NFL teams attended his pro day, including defensive back coaches from the Pittsburgh Steelers, Minnesota Vikings, Philadelphia Eagles, and Tennessee Titans.

[7] He also attended private workouts and visits with multiple teams, including the Dallas Cowboys and Baltimore Ravens.

[8] Head coach Bill O'Brien named Johnson the third cornerback on the Texans' depth chart, behind veterans Johnathan Joseph and Kareem Jackson.

[14][15] He made his professional debut in the Texans' season opener against the Kansas City Chiefs and recorded two solo tackles in the 27–20 loss.

Johnson finished his rookie season with a total of 54 combined tackles, nine pass deflections, and an interception while playing in all 16 games and starting ten.

[16] The following season, Johnson returned as the Texans' third cornerback and made two solo tackles in their season-opening victory over the Chicago Bears.

[18] Johnson entered training camp competing with Jackson for the job as the starting cornerback after Bouye signed with the Jacksonville Jaguars.

[19] On October 29, 2017, he played in his first game since returning from his MCL injury and recorded five combined tackles and deflected a pass during a 41–38 loss to the Seattle Seahawks.