Florian was a former UFC lightweight contender and the runner-up in the middleweight division on the first season of The Ultimate Fighter reality show. He has fought at middleweight, welterweight and lightweight in the UFC. He has fought for the UFC lightweight title twice, against Sean Sherk in 2006 and B.J. Penn in 2009, losing both times. Florian is also dropping down to featherweight (145 pounds).
He most recently fought undefeated Gray Maynard for the number-one contendership to the title yet again. Maynard dominated Florian absolutely en route to a unanimous decision to earn the number-one contendership.
Florian was next set to face fellow contender Evan Dunham after WEC featherweight champion Jose Aldo declined to fight Florian. The fight was then announced to headline the second Fight for the Troops free event. Unfortunately about a month before the bout was set to occur, Florian had to withdraw with an injury. Melvin Guillard stepped up from the undercard to face Dunham.
After Guillard defeated Dunham via brutal knockout, Florian called out Guillard predictably. Guillard refused the fight. Florian afterwards decided to drop down to featherweight. He made his featherweight debut against contender Diego Nunes. Florian defeated Nunes via unanimous decision. That night at the post-fight press conference, Dana White announced that Florian had already earned a featherweight title shot.
Florian next faced P4P elite Jose Aldo for the UFC featherweight title, losing via a close unanimous decision. After the loss, Florian contemplated retirement heavily but in the end, he decided that his love for the sport had not diminished and he simply moved back up to lightweight.
Florian didn't find a fight there however and worked as a commentator for the UFC alongside Jon Anik for several events in late 2011 and early 2012 before retiring from fighting at the TUF Live finale weigh-ins on May 31, 2012. He continued commentating.
- Kenny Florian vs. Bobby McAndrews
- Diego Sanchez vs. Kenny Florian - The fight was the UFC debut of both men and it was to decide the middleweight winner of the first season of The Ultimate Fighter.
- Kenny Florian vs. Alex Karalexis - The fight was Florian's welterweight debut and it was Alex Karalexis's first loss.
- Kenny Florian vs. Sam Stout - The fight was Florian's lightweight debut.
- Sean Sherk vs. Kenny Florian - The fight was for the vacant UFC lightweight title. The fight was Sean Sherk's debut at lightweight. The fight was considered one of the top ten bloodiest fights in UFC history.
- Kenny Florian vs. Din Thomas - The fight was controversial because Florian landed a groin kick early in the first round before Din Thomas blew out his knee, allowing Florian to take his back and choking him out for the tap with thirty seconds left in the round.
- Kenny Florian vs. Joe Lauzon
- Kenny Florian vs. Roger Huerta - The fight was Roger Huerta's first loss inside the UFC, snapping a sixteen-fight win streak.
- Kenny Florian vs. Joe Stevenson - The fight was for a shot at the UFC lightweight title.
- B.J. Penn vs. Kenny Florian - The fight, in 2009, was for the UFC lightweight championship with B.J. Penn defending. The fight was Florian's second shot at the lightweight belt since his fight for the vacant belt with Sean Sherk in 2006.
- Kenny Florian vs. Clay Guida - Both men were coming off losses, Florian in a second failed bid for the lightweight title against B.J. Penn and Clay Guida against Diego Sanchez.
- Kenny Florian vs. Takanori Gomi - The fight was the UFC debut of Takanori Gomi.
- Gray Maynard vs. Kenny Florian - The fight was for the number-one contendership of the UFC lightweight title.
- Jose Aldo vs. Kenny Florian - The fight was for the UFC featherweight title with Jose Aldo defending. After the fight, Florian retired.