| Sieg | 21-12-1 | Alberto Rodriguez | Submission (Rear-Naked Choke) |  | Combate: Hidalgo | Dec 07, 2019 | 1 | 3:10 | Hidalgo, Texas |
| Sieg | 20-12-1 | Chuck Liddell  | KO (Punches) |  | Golden Boy MMA: Liddell vs Ortiz 3 | Nov 24, 2018 | 1 | 4:24 | Inglewood, California, United States |
| Sieg | 19-12-1 | Chael Sonnen | Submission (rear-naked choke) |  | Bellator 170: Ortiz vs Sonnen | Jan 21, 2017 | 1 | 2:03 | Inglewood, California, United States |
| Niederlage | 18-12-1 | Liam McGeary  | Submission (Inverted Triangle Choke) |  | Bellator 142: Dynamite | Sep 19, 2015 | 1 | 4:41 | SAP Center, San Jose, United States |
| Sieg | 18-11-1 | Stephan Bonnar | Decision (split) |  | Bellator 131 | Nov 15, 2014 | 3 | 5:00 | San Diego, United States |
| Sieg | 17-11-1 | Alexander Shlemenko  | Technical Submission |  | Bellator 120 | May 17, 2014 | 1 | 2:27 | Southaven, United States |
| Niederlage | 16-11-1 | Forrest Griffin | Decision (unanimous) | | UFC 148: Silva vs Sonnen 2 | Jul 07, 2012 | 3 | 5:00 | Las Vegas, United States |
| Niederlage | 16-10-1 | Antonio Rogério Nogueira  | TKO (punches to the body) |  | UFC 140 | Dec 10, 2011 | 1 | 3:15 | Toronto, Ontario, Canada |
| Niederlage | 16-9-1 | Rashad Evans | TKO |  | UFC 133 | Aug 06, 2011 | 2 | 4:48 | Philadelphia, United States |
| Sieg | 16-8-1 | Ryan Bader | Submission (guillotine choke) | | UFC 132 | Jul 02, 2011 | 1 | 1:56 | Las Vegas, United States |
| Niederlage | 15-8-1 | Matt Hamill | Decision (unanimous) |  | UFC 121 | Oct 23, 2010 | 3 | 5:00 | Anaheim, United States |
| Niederlage | 15-7-1 | Forrest Griffin | Decision (split) |  | UFC 106 | Nov 21, 2009 | 3 | 5:00 | Las Vegas, United States |
| Niederlage | 15-6-1 | Lyoto Machida | Decision (unanimous) | | UFC 84 | May 24, 2008 | 3 | 5:00 | Las Vegas, United States |
| Unentschieden | 15-5-1 | Rashad Evans | Draw (unanimous) | | UFC 73 | Jul 07, 2007 | 3 | 5:00 | Sacramento, United States |
| Niederlage | 15-5 | Chuck Liddell | TKO (punches) |  | UFC 66 | Dec 30, 2006 | 3 | 3:59 | Las Vegas, Nevada |
| Sieg | 15-4 | Ken Shamrock | TKO (punches) | | Ortiz vs. Shamrock 3 | Oct 10, 2006 | 1 | 2:22 | Hollywood, United States |
| Sieg | 14-4 | Ken Shamrock | TKO (elbows) | | UFC 61 | Jul 08, 2006 | 1 | 1:18 | Las Vegas, Nevada |
| Sieg | 13-4 | Forrest Griffin | Decision (split) | | UFC 59 | Apr 15, 2006 | 3 | 5:00 | Anaheim, United States |
| Sieg | 12-4 | Vitor Belfort | Decision (split) | | UFC 51 | Feb 05, 2005 | 3 | 5:00 | Las Vegas, United States |
| Sieg | 11-4 | Patrick Côté  | Decision (unanimous) | | UFC 50 | Oct 22, 2004 | 3 | 5:00 | Atlantic City, United States |
| Niederlage | 10-4 | Chuck Liddell | TKO (punches) |  | UFC 47 | Apr 02, 2004 | 2 | 0:38 | Las Vegas, Nevada |
| Niederlage | 10-3 | Randy Couture | Decision (unanimous) |  | UFC 44 | Sep 26, 2003 | 5 | 5:00 | Las Vegas, Nevada |
| Sieg | 10-2 | Ken Shamrock | TKO (corner stoppage) | | UFC 40 | Nov 22, 2002 | 3 | 5:00 | Las Vegas, Nevada |
| Sieg | 9-2 | Vladimir Matyushenko  | Decision (unanimous) | | UFC 33 | Sep 28, 2001 | 5 | 5:00 | Las Vegas, United States |
| Sieg | 8-2 | Elvis Sinosic | TKO (punches and elbows) | | UFC 32 | Jun 29, 2001 | 1 | 3:32 | East Rutherford, United States |
| Sieg | 7-2 | Evan Tanner | KO (slam) | | UFC 30 | Feb 23, 2001 | 1 | 0:30 | Atlantic City, New Jersey |
| Sieg | 6-2 | Yuki Kondo  | Submission (neck crank) | | UFC 29 | Dec 16, 2000 | 1 | 1:51 | Tokyo, Japan |
| Sieg | 5-2 | Wanderlei Silva | Decision (unanimous) | | UFC 25 | Apr 14, 2000 | 5 | 5:00 | Tokyo, Japan |
| Niederlage | 4-2 | Frank Shamrock | Submission (punches) |  | UFC 22 | Sep 24, 1999 | 4 | 4:50 | Lake Charles, United States |
| Sieg | 4-1 | Guy Mezger | TKO (punches) | | UFC 19 | Mar 05, 1999 | 1 | 9:56 | Bay St. Louis, United States |
| Sieg | 3-1 | Jerry Bohlander | TKO (cut) | | UFC 18 | Jan 08, 1999 | 1 | 14:31 | New Orleans, United States |
| Sieg | 2-1 | Jeremy Screeton | Submission (knees) | | West Coast NHB Championships 1 | Dec 08, 1998 | 1 | 0:16 | Los Angeles, United States |
| Niederlage | 1-1 | Guy Mezger | Submission | | UFC 13 | May 30, 1997 | 1 | 3:00 | Augusta, United States |
| Sieg | 1-0 | Wes Albritton | TKO (punches) | | UFC 13 | May 30, 1997 | 1 | 0:31 | Augusta, Georgia |
