Horford's older brother, Al, confirmed the decision to The Associated Press before Saturday's NBA playoff game between the Atlanta Hawks and the Indiana Pacers. Al Horford spent three seasons at Florida, helping the Gators win consecutive national championships in 2006 and '07.
''It's exciting,'' Al Horford said. ''More than anything, I just want him to be successful. I think at Florida he's going to have that chance.''
The 6-foot-10 Jon Horford averaged 3.8 points and 4.2 rebounds in 13.8 minutes a game last season, helping the Wolverines win the Big Ten despite losing big man Mitch McGary to a back injury.
McGary entered the NBA draft Friday, saying he had little choice after testing positive for marijuana and facing a one-year ban. With McGary gone, Horford likely would have seen significant playing time with the Wolverines.
Instead, he will take his chances in Gainesville, where Florida should have a stacked frontcourt. The Gators lose center Patric Young and forwards Will Yeguete and Casey Prather to graduation, but return 6-foot-10 center Damontre Harris, 6-10 forward Chris Walker and 6-8 forward Dorian Finney-Smith. They also add former Duke forward Alex Murphy, who transferred to Florida last December, and highly touted incoming freshman Devin Robinson, a 6-8 forward from Chesterfield, Va.
Horford is scheduled to complete his undergraduate degree in May. So he's taking advantage of an NCAA rule that allows graduate students to change schools without having to sit out a year under normal transfer policies.
Al Horford said Florida head coach Billy Donovan was a big reason for his brother's decision.
''I think Coach Donovan having a relationship with our family and me playing for him, to him, it made sense,'' Horford said. ''He believes in what Coach is trying to accomplish at Florida.''
Horford added that he will try to attend as many games as possible next season.
''Oh, I'm going to be in Gainesville, there's no question about it,'' he said. ''I'm going to be supportive.''
Jon Horford will take the last of Florida's 13 scholarships for the 2014-15 season. Of those 13 players, five are transfers. Horford, Harris (South Carolina), Finney-Smith (Virginia Tech), Murphy (Duke) and guard Eli Carter (Rutgers) all began their careers elsewhere before landing in Gainesville.
Donovan has had at least one transfer on his roster in each of the past six years, beginning with center Vernon Macklin (Georgetown) during the 2008-09 season.
AP sports writer Paul Newberry contributed to this report.