Fournette initially thanked LSU coach Ed Orgeron for "his decision for not letting me play" in the bowl so that his injured ankle could continue healing, but the star running back eventually clarified that the decision was mutual.
"Me and Coach O came to the decision," Fournette said. "We really thought it was best for me."
Fournette, the No. 1 prospect on ESPN analyst Todd McShay's board for the 2017 NFL draft, previously had announced that he would enter the draft after the season ended.
LSU will play Louisville in the Buffalo Wild Wings Citrus Bowl on Dec. 31.
This will be the fifth game this season that Fournette, a junior, has missed. He has been hampered by a lingering ankle injury -- a high- and low-ankle sprain, plus a bone bruise -- that he initially suffered in an August scrimmage.
He managed to rush for 843 yards and eight touchdowns in seven games, but rarely looked like the Heisman Trophy candidate who ran for a school-record 1,953 yards a season ago.
"I'm not a quitter at all," said Fournette, who earned second-team All-SEC honors despite missing half the season. "I tried to play through the injury as best as I could. So it was hard knowing that the hard work that I put in didn't build up to the season."
Fournette said the ankle is now 85 to 90 percent healthy after sitting out since the Tigers' Nov. 19 loss to Florida.
"It's getting better," Fournette said. "Over time that we had break, I was just going to rehab, going to see the doctors and stuff, so it's getting better."
The New Orleans native called it a "hurtful feeling" that he was unable to play a full season and contend for a national championship in his final season at his home-state school.
But Orgeron pointed to the impact Fournette had on the LSU program. He singled out Fournette's 228-yard, three-touchdown game against Auburn last season, and a 284-yard effort on just 16 carries against Ole Miss this fall.
"We are grateful for all the years Leonard gave us, all the great memories, all the great games," Orgeron said. "One of the most dominating performances I've ever seen as a coach [was] against Auburn, and against Ole Miss this year. But more than that, Leonard's on track to graduate in May.
"Leonard was a great teammate. Every day he came to work. He was a joy to coach. Players love him. Little kids across the country emulate him, want to be like him. We know this is a tough decision for Leonard, but he has a bright future ahead of himself. The Tiger family wishes him the best. He will always be an LSU Tiger."