The schools will play in Gainesville on Sept. 15, 2018, with the Rams getting $2 million for the game.
The game is part of the $7 million buyout the Gators agreed to pay Colorado State when they hired McElwain in December. Additionally, McElwain is required to pay his former school $2 million. Florida is paying Colorado State $3 million through 2020 in annual installments of $500,000.
"That was all part of the gig," McElwain said Thursday. "I'm excited about it. I know that they've got really good players and they'll come in and beat our tail when that time is."
Colorado State hired former Georgia assistant Mike Bobo to replace McElwain.