| Niederlage | 16-14-2 | Clay Guida  | Decision (Unanimous) |  | UFC 237: Namajunas vs Andrade | May 11, 2019 | 3 | 5:00 | Rio de Janeiro, Brazil |
| Niederlage | 16-13-2 | Ryan Hall | Submission (heel hook) |  | UFC 232 | Dec 29, 2018 | 1 | 2:46 | Inglewood, California, United States |
| Niederlage | 16-12-2 | Dennis Siver  | Decision (Majority) |  | UFC Fight Night 112: Chiesa vs Lee | Jun 25, 2017 | 3 | 5:00 | Oklahoma City, Oklahoma, United States |
| Niederlage | 16-11-2 | Yair Rodriguez  | TKO (front kick and punches) |  | UFC Fight Night 103: Rodriguez vs Penn | Jan 15, 2017 | 2 | 0:24 | Phoenix, Arizona, United States |
| Cancelled Bout | | Dennis Siver | - |  | UFC 199: Rockhold vs Bisping 2 | Jun 04, 2016 | - | - | Inglewood, California, United States |
| Niederlage | 16-10-2 | Frankie Edgar | TKO (strikes) |  | UFC: The Ultimate Fighter 19 Finale | Jul 06, 2014 | 3 | 4:16 | Las Vegas, United States |
| Niederlage | 16-9-2 | Rory MacDonald  | Decision (unanimous) |  | UFC on Fox: Henderson vs. Diaz | Dec 08, 2012 | 3 | 5:00 | Seattle, Washington, US |
| Niederlage | 16-8-2 | Nick Diaz | Decision (unanimous) | | UFC 137 | Oct 29, 2011 | 3 | 5:00 | Las Vegas, Nevada, US |
| Unentschieden | 16-7-2 | Jon Fitch | Draw (majority) |  | UFC 127 | Feb 27, 2011 | 3 | 5:00 | New South Wales, Australia |
| Sieg | 16-7-1 | Matt Hughes | KO (punches) |  | UFC 123 | Nov 20, 2010 | 1 | 0:21 | Auburn Hills, Michigan, US |
| Niederlage | 15-7-1 | Frankie Edgar | Decision (unanimous) |  | UFC 118 | Aug 28, 2010 | 5 | 5:00 | Boston, United States |
| Niederlage | 15-6-1 | Frankie Edgar | Decision (unanimous) |  | UFC 112 | Apr 10, 2010 | 5 | 5:00 | Abu Dhabi, UA Emirates |
| Sieg | 15-5-1 | Diego Sanchez | TKO (doctor stoppage) |  | UFC 107 | Dec 12, 2009 | 5 | 2:37 | Memphis, Tennessee, US |
| Sieg | 14-5-1 | Kenny Florian | Submission (rear-naked choke) |  | UFC 101 | Aug 08, 2009 | 4 | 3:54 | Philadelphia |
| Niederlage | 13-5-1 | Georges St. Pierre | TKO (corner stoppage) |  | UFC 94 | Jan 31, 2009 | 4 | 5:00 | Las Vegas, United States |
| Sieg | 13-4-1 | Sean Sherk | TKO (flying knee & punches) | | UFC 84 | May 24, 2008 | 3 | 5:00 | Las Vegas, Nevada, US |
| Sieg | 12-4-1 | Joe Stevenson | Submission (rear-naked choke) | | UFC 80 | Jan 19, 2008 | 2 | 4:02 | Newcastle upon Tyne, UK |
| Sieg | 11-4-1 | Jens Pulver | Submission (rear-naked choke) | | The Ultimate Fighter 5 Finale | Jun 23, 2007 | 2 | 3:12 | Las Vegas, Nevada, US |
| Niederlage | 10-4-1 | Matt Hughes | TKO (punches) |  | UFC 63 | Sep 23, 2006 | 3 | 3:53 | Anaheim, California, US |
| Niederlage | 10-3-1 | Georges St. Pierre | Decision (split) |  | UFC 58 | Mar 04, 2006 | 3 | 5:00 | Las Vegas, United States |
| Sieg | 10-2-1 | Renzo Gracie  | Decision (unanimous) |  | K-1: World Grand Prix Hawaii | Jul 29, 2005 | 3 | 5:00 | Honolulu, Hawaii, United States |
| Niederlage | 9-2-1 | Lyoto Machida | Decision (unanimous) |  | List of HERO's events K-1 Hero's 1 | Mar 26, 2005 | 3 | 5:00 | Saitama, Saitama, Japan |
| Sieg | 9-1-1 | Rodrigo Gracie | Decision (unanimous) |  | K-1 Rumble on the Rock 6 | Nov 20, 2004 | 3 | 5:00 | Honolulu, Hawaii, United States |
| Sieg | 8-1-1 | Duane Ludwig | Submission (arm-triangle choke) |  | K-1 MMA: Romanex | May 22, 2004 | 1 | 1:45 | Saitama, Saitama, Japan |
| Sieg | 7-1-1 | Matt Hughes | Submission (rear-naked choke) |  | UFC 46 | Jan 31, 2004 | 1 | 4:39 | Las Vegas, Nevada, US |
| Sieg | 6-1-1 | Takanori Gomi  | Submission (rear-naked choke) | | K-1 Rumble on the Rock 4 | Oct 10, 2003 | 3 | 2:35 | Honolulu, Hawaii, United States |
| Unentschieden | 5-1-1 | Caol Uno | Draw (split) |  | UFC 41 | Feb 28, 2003 | 5 | 5:00 | Atlantic City, New Jersey, US |
| Sieg | 5-1 | Matt Serra | Decision (unanimous) | | UFC 39 | Sep 27, 2002 | 3 | 5:00 | Uncasville, Connecticut, US |
| Sieg | 4-1 | Paul Creighton | TKO (punches) | | UFC 37 | May 10, 2002 | 2 | 3:23 | Bossier City, Louisiana, US |
| Niederlage | 3-1 | Jens Pulver | Decision (majority) | | UFC 35 | Jan 11, 2002 | 5 | 5:00 | Uncasville, Connecticut, US |
| Sieg | 3-0 | Caol Uno | KO (punches) | | UFC 34 | Nov 02, 2001 | 1 | 0:11 | Las Vegas, Nevada, US |
| Sieg | 2-0 | Din Thomas | KO (knee and punches) | | UFC 32 | Jun 29, 2001 | 1 | 2:42 | East Rutherford, New Jersey, US |
| Sieg | 1-0 | Joey Gilbert | TKO (punches) | | UFC 31 | May 04, 2001 | 1 | 4:57 | Atlantic City, New Jersey, US |
