He played college football for the LSU Tigers, and was selected by the Jacksonville Jaguars with the fourth overall pick in the 2017 NFL draft.

He won the 2013 USA Today High School Football Offensive Player of the Year and was named the top-ranked recruit in 2014 senior class according to ESPN, 247Sports.com, and CBS Sports.

However, he struggled with several injuries and suspensions and as a result, his relationship with the franchise soured, eventually leading to his release after just three seasons with the team.

He then signed with the Buccaneers, with whom he played a large part in winning Super Bowl LV over the Kansas City Chiefs.

Raised in the 7th Ward of New Orleans by his parents Leonard Jr. and Lory, Fournette grew up in a troubled area that was often affected by violence and gang activity, especially after Hurricane Katrina hit in 2005.

Fournette credited Katrina as kick-starting his football career after he moved to Houston and back within a year because of the hurricane evacuation.

Early in the season, he had a heralded performance with two touchdowns and 262 yards rushing against Malachi Dupre's John Curtis Christian, which was nationally televised by ESPN2.

[8] St. Augustine ended the season with a 9–2 record and an appearance in the LHSAA Division I semifinal game, where they were upset 31–28 by Archbishop Rummel High School.

After the season, Fournette participated in the Under Armour All-America Game where he caught a 36-yard touchdown pass and rushed for 43 yards on nine carries.

Unanimously regarded as the best running back prospect of his class, Fournette was one of the most highly recruited players ever to come out of Louisiana.

[11] At the 2014 Under Armour All-America Game, Fournette announced his decision to attend Louisiana State University (LSU).

[12] Fournette attended and played college football for LSU from 2014 to 2016 under head coaches Les Miles and Ed Orgeron.

[17] In the fifth week of the season, the New Mexico State Aggies traveled to Death Valley to face the #17 LSU Tigers, and Fournette ran for 122 yards on 18 carries and scored two touchdowns.

[19] On October 11 against SEC rival Florida, Fournette rushed the ball 27 times for 140 yards and two touchdowns to help LSU secure a 30–27 last-second win in The Swamp.

[21] LSU ran the ball 12 times for 92 yards on a 13-play, 95-yard touchdown drive to upset the Rebels by a score of 10–7 in Death Valley.

[23][24] Fournette started his sophomore season with a strong performance of 159 rushing yards and three touchdowns against Mississippi State.

Entering his junior season, Fournette was expected to contend for the Heisman Trophy, and was one of the preseason favorites to win the award.

He re-injured it against SEC West rival Auburn on September 24 in a 101-yard rushing effort, causing him to miss the next two games.

With his ankle still not fully healed, Fournette was not expected to play against Florida on November 19, and did not suit up for pregame warm-ups.

[49] Due to the injury, he did not travel with the team to College Station to face Texas A&M in the final game of the regular season.

[53] Fournette finished his college career having rushed for 3,830 yards, the fourth-most by a player in LSU history behind Charles Alexander, Dalton Hilliard, and Kevin Faulk.

[54] Att Coming out of college, Fournette was highly touted as a top ten pick in the upcoming draft and was ranked as the third best prospect going into the NFL Combine.

He arrived at the NFL combine weighing in five pounds heavier than his playing weight in college and opted to only participate in the vertical jump and 40-yard dash.

He was ranked the top overall running back prospect by NFLDraftScout.com, and second behind Florida State's Dalvin Cook by Pro Football Focus and Sports Illustrated.

[67] In Week 6 against the Los Angeles Rams, Fournette carried 21 times for 130 yards, including a 75-yard touchdown run on the Jaguars' first play from scrimmage.

[72] In the Wild Card Round against the Buffalo Bills, Fournette struggled, rushing for 57 yards on 21 carries as the Jaguars won 10–3.

[73] In the Divisional Round against the Steelers, he briefly left the game with an ankle injury, but returned and finished with 109 yards and three touchdowns as the Jaguars won 45–42.

[115] On December 23, Fournette was elevated from the practice squad due to Ty Johnson being inactive because of a shoulder injury.

[123][124] On June 8, 2020, Fournette led a peaceful march of about 700 people, including police officers, in downtown Jacksonville to protest the murder of George Floyd.