A native of Lake City, Florida, Jernigan attended Columbia High School, where he was an All-American defensive lineman and teammates with All-American offensive linemanLaremy Tunsil for his junior and senior year. As a junior, Jernigan registered 131 tackles, 27 tackles for loss, 12 sacks, three forced fumbles and three fumble recoveries and was a 3A All-State selection. In his senior season, he added 77 tackles, 32 tackles for loss, 14 sacks and one interception. Regarded nationally as one of the best defensive lineman in his class, he participated in the 2011 U.S. Army All-American Bowl and was a USA Today All-USA selection. He was also a member of the track & field team. Considered a four-star recruit by Rivals.com, Jernigan was listed as the No. 2 defensive lineman in his class, behind only Anthony Johnson. Recruited by dozens of schools, Jernigan took official visits to Florida State, Michigan, Louisiana State, and Tennessee, before committing to the Seminoles on National Signing Day 2011.
College career
In his true freshman season, Jernigan served as back-up to Everett Dawkins at defensive tackle for the Seminoles. He saw action in all 13 games and led all FSU interior defensive linemen with 30 tackles, six tackles for loss and 2.5 quarterback sacks. Jernigan was named winner of the Devaughn Darling Award given to the top newcomer on defense at the team's annual banquet. He was also named a Freshman All-American by the Football Writers Association of America. Still serving as Dawkins' reserve in 2012, Jernigan was one of the leading tacklers on the team with 46. He also ranked fourth on FSU in tackles for loss with eight. In his final four games, Jernigan recorded 22 tackles, two tackles for loss and a sack. In the 2012 ACC Championship Game against Georgia Tech, he recorded the team's only sack, was second on the squad with 1.5 TFL and was third on the team with nine tackles. Jernigan led Florida State with 11 tackles for loss in 2013. Jernigan finished this season with 63 tackles, including 4.5 sacks and was a second-team AP All-American. Jernigan announced on January 9, 2014 that he would forgo his senior season and enter the 2014 NFL Draft.
Professional career
Baltimore Ravens
Projected a first-rounder by CBS Sports, Jernigan was drafted by the Baltimore Ravens in the second round of the 2014 NFL Draft. In 2016, Jernigan started 15 of 16 games, finishing second on the team with five sacks.
On April 4, 2017, the Ravens traded Jernigan to the Philadelphia Eagles along with the 99th overall pick in the 2017 NFL Draft in exchange for the Eagles' 74th pick in the draft. After starting the first nine games of the season with the Eagles, Jernigan signed a four-year, $48 million contract extension with the team. Jernigan finished the season with 29 tackles and 2.5 sacks. The Eagles won Super Bowl LII after defeating the New England Patriots 41-33 with Jernigan recording one tackle. After the 2017 season Jernigan had surgery on his back on May 3, 2018. He was placed on the reserve/non-football injury list to start the 2018 season. He was activated off the NFI list on November 20, 2018. On March 4, 2019, the Eagles declined the option on Jernigan's option, making him an unrestricted free agent. On April 25, 2019, the Eagles re-signed Jernigan to a one-year deal.
