Billy Donovan won two national championships as Florida's men's basketball coach. Oklahoma City has never won an NBA title.
The Thunder sees him as the "perfect fit" as its next head coach. The organization announced Thursday that Donovan will replace Scott Brooks, who was fired last week.
"He is the perfect fit for our organization and for our community and we look forward to a long and successful relationship," Thunder chairman Clayton Bennett said.
Donovan, who recently signed a one-year contract extension that would have paid him an average of $4 million through 2020, led the Gators to four Final Fours, seven Elite Eights and 14 NCAA tournament berths in 19 years.
He will be under pressure to produce a winner in Oklahoma City immediately. His roster will include 2013-14 NBA MVP Kevin Durant and 2014-15 scoring champion Russell Westbrook.
Facing numerous injuries to key players, the Thunder finished 45-37 and missed the playoffs this season.
"I knew that it would take a unique opportunity to leave the University of Florida, and that is clearly how I look at this situation," Donovan said.