He earned a fourth-place finish in the shot put event at the 2008 UIL 1A State Championships, with a top-throw of 15.21 meters (49 ft 7 in).

In his sole year at Kilgore, Johnson amassed 510 passing yards for 3 touchdowns and 7 interceptions with a 52.4% completion rate while at quarterback.

Kittle was amazed by Johnson's footwork and natural pass blocking abilities and immediately switched him to offensive tackle.

[7] Throughout Senior Bowl practices, Johnson demonstrated impressive footwork, body control, and balance while diagnosing pass rushes and disrupting them.

He was named a top standout during practice by NFL analyst Bucky Brooks and immensely helped his draft stock to put himself in the first round discussion.

[8] On January 26, 2013, he played offensive tackle in the Reese's Senior Bowl and was part of Detroit Lions' head coach Jim Schwartz's South team that defeated the North 21–16.

[9] On March 13, 2013, Johnson attended Oklahoma's pro day, along with Landry Jones, Tony Jefferson, Demontre Hurst, Kenny Stills, Stacy McGee, and 19 other prospects.

[10][11] During the draft process, Johnson attended multiple private workouts and visits, including the Carolina Panthers, New York Jets, and Philadelphia Eagles.

[17] He was the third offensive tackle selected in 2013, behind Central Michigan's Eric Fisher and Texas A&M's Luke Joeckel.

[20] He became the apparent starting right tackle during training camp when it was reported that Kelly would miss the majority of the season after undergoing back surgery.

[21] He made his first career start and professional regular season debut in the Eagles' season-opening 33–27 victory at the Washington Redskins.

He started all 16 regular season games as a rookie and helped the Eagles finish first in the NFC East with a 10–6 record.

Johnson entered training camp slated as the Eagles' starting right tackle, opposite Jason Peters.

[34] The Eagles finished fourth in the NFC East with a 7–9 record in their first season under head coach Doug Pederson.

Johnson remained in the concussion protocol and missed the Eagles' next game that took place five days later on Thursday Night Football.

[37] Near the end of the season, Johnson received an overall grade of 85.2 and ranked fifth amongst all offensive tackles by Pro Football Focus.

[47] On December 26, it was announced that Johnson would miss the remainder of the regular season after suffering a torn tendon in his abdomen.

[57] On April 6, 2024, Johnson and former Eagles teammate Jason Kelce (wearing Luchador masks) participated in WrestleMania XL, helping Rey Mysterio and Andrade win their match.