As a child, Florian excelled in many sports including soccer, tennis, and the martial arts. In high school and college, he focused mainly on soccer and put the martial arts aside. He played soccer at Boston College, and earned Big-East academic all-star status. He graduated with a degree in Communications.
After college, his interests turned towards mixed martial arts, and he earned a black belt in Brazilian Jiu-Jitsu from Prof. Roberto Maia of Boston Brazilian Jiu-Jitsu (Gracie Barra Boston).
Florian made his MMA debut fight in January 2003 at Mass Destruction 10, defeating Jason Giroux via TKO (strikes). Kenny made another appearance in the Mass Destruction Promotion at MD - 15 and brought home a sweet victory over Bobby McAndrews by a submission (kimura). Following those victories, Kenny suffered his first loss to UFC regular Drew Fickett via decision at Combat Zone 7-Gravel Pit on July 10 2004.
Kenny went on to compete on the first season of The Ultimate Fighter as a middleweight, losing at the finale in the first round to Sanchez due to strikes.
Following his loss to Sanchez, Florian returned at the first Ultimate Fight Night to defeat fellow TUF 1 competitor Alex Karalexis with a vicious cut across the nose. Picking up momentum, Kenny went on to face Muay Thai competitor Kit Cope, winning with a rear naked choke submission early in round 2. Florian earned a title shot after defeating Canadian TKO Lightweight champion Sam Stout at The Ultimate Fighter 3 season finale; Florian won in the first round by rear naked choke.
On October 14 2006, Florian fought Sean Sherk for the UFC Lightweight championship title at UFC 64: Unstoppable and lost via unanimous decision.
On April 5 2007, at UFC Fight Night 9 Florian defeated Japanese fighter Dokonjonosuke Mishima via rear naked choke submission.
On July 7 2007, at UFC 73, he defeated UFC newcomer Alvin Robinson via submission due to strikes in the first round.
In one of Florian's more recent fights he managed to get another win via submission due to a rear naked choke against Din Thomas at UFC Fight Night 11. Thomas injured his knee while attempting a takedown during the bout. Thomas was originally slated to face off against Spencer Fisher, but Fisher had to pull out due to a staph infection. Florian took his place.
On April 2 2008 Florian next defeated the young up and comer Joe Lauzon at UFC Fight Night 13 by TKO Strikes from Mount, early on in just the 2nd round to secure his spot among the UFC's Top Light Weight Contenders.
On April 19, Florian filled in for Joe Rogan as the color commentator for UFC 83.
At UFC 87 on August 9 2008 Florian defeated Roger Huerta by unanimous decision. Next up will be Joe Stevenson at UFC 91 on November 15th.
He currently hosts an online show called MMA Live for ESPN.com.
Florian contributes to the show with his MMA experience and his perspective as a fighter.
| Result | Record | Opponent | Method | Event | Date | Round | Time | Notes |
| Win | 10-3 | Roger Huerta | Decision (unanimous) | UFC 87: Seek and Destroy | 08/09/2008 | 3 | 5:00 | |
| Win | 9-3 | Joe Lauzon | TKO (Strikes) | UFC Fight Night 13 | 04/02/2008 | 2 | 3:28 | Won Fight of the Night Honors |
| Win | 8-3 | Din Thomas | Submission (Rear Naked Choke) | UFC Fight Night 11 | 09/19/2007 | 1 | 4:30 | |
| Win | 7-3 | Alvin Robinson | Submission (Strikes) | UFC 73: Stacked | 7/7/2007 | 1 | 4:30 | |
| Win | 6-3 | Dokonjonosuke Mishima | Submission (Rear Naked Choke) | UFC Fight Night 9 | 4/5/2007 | 3 | 3:57 | |
| Loss | 5-3 | Sean Sherk | Decision (Unanimous) | UFC 64: Unstoppable | 10/14/2006 | 5 | 5:00 | For Vacant UFC Lightweight Championship |
| Win | 5-2 | Sam Stout | Submission (Rear Naked Choke) | UFC Ultimate Fighter 3 Finale | 6/24/2006 | 1 | 1:46 | |
| Win | 4-2 | Kit Cope | Submission (Rear Naked Choke) | UFC Ultimate Fighter 2 Finale | 11/5/2005 | 2 | 0:37 | |
| Win | 3-2 | Alex Karalexis | TKO (Cut) | UFC Ultimate Fight Night | 8/6/2005 | 2 | 2:52 | |
| Loss | 2-2 | Diego Sanchez | TKO (strikes) | UFC Ultimate Fighter Finale | 4/9/2005 | 1 | 2:49 | |
| Loss | 2-1 | Drew Fickett | Decision | Combat Zone 7: Gravel Pit | 7/10/2004 | 3 | 5:00 | |
| Win | 2-0 | Bobby McAndrews | Submission (Kimura) | Mass Destruction 15 | 2/21/2004 | 1 | 1:57 | |
| Win | 1-0 | Jason Giroux | TKO (Strikes) | Mass Destruction 10 | 1/25/2003 | 1 | N/A |