| Result | Record | Opponent | Method | Event | Date | Round | Time | Location | Notes |
| Loss | 15–8–1 | Matt Hamill | Decision (Unanimous) | UFC 121: Lesnar vs Velasquez | October 23, 2010 | 3 | 5:00 | Anaheim, California | |
| Loss | 15–7–1 | Forrest Griffin | Decision (Split) | UFC 106: Ortiz vs Griffin 2 | November 21, 2009 | 3 | 5:00 | Las Vegas, Nevada | |
| Loss | 15–6–1 | Lyoto Machida | Decision (Unanimous) | UFC 84: Ill Will | May 24, 2008 | 3 | 5:00 | Las Vegas, Nevada | |
| Draw | 15–5–1 | Rashad Evans | Draw (Unanimous) | UFC 73: Stacked | July 7, 2007 | 3 | 5:00 | Sacramento, California | Ortiz was penalized a point for holding on to the fence. |
| Loss | 15–5 | Chuck Liddell | TKO (Punches) | UFC 66: Liddell vs. Ortiz 2 | December 30, 2006 | 3 | 3:59 | Las Vegas, Nevada | For UFC Light Heavyweight Championship |
| Win | 15–4 | Ken Shamrock | TKO (Punches) | Ortiz vs. Shamrock 3: The Final Chapter | October 10, 2006 | 1 | 2:22 | Hollywood, Florida | Won Knockout Of The Night. |
| Win | 14–4 | Ken Shamrock | TKO (Elbows) | UFC 61: Bitter Rivals | July 8, 2006 | 1 | 1:18 | Las Vegas, Nevada | |
| Win | 13–4 | Forrest Griffin | Decision (Split) | UFC 59: Reality Check | April 15, 2006 | 3 | 5:00 | Anaheim, California | |
| Win | 12–4 | Vitor Belfort | Decision (Split) | UFC 51: Super Saturday | February 5, 2005 | 3 | 5:00 | Las Vegas, Nevada | |
| Win | 11–4 | Patrick Côté | Decision (Unanimous) | UFC 50: The War of '04 | October 22, 2004 | 3 | 5:00 | Atlantic City, New Jersey | |
| Loss | 10–4 | Chuck Liddell | KO (Punches) | UFC 47: It's On! | April 2, 2004 | 2 | 0:38 | Las Vegas, Nevada | |
| Loss | 10–3 | Randy Couture | Decision (Unanimous) | UFC 44: Undisputed | September 26, 2003 | 5 | 5:00 | Las Vegas, Nevada | Lost UFC Light Heavyweight Championship |
| Win | 10–2 | Ken Shamrock | TKO (Corner Stoppage) | UFC 40: Vendetta | November 22, 2002 | 3 | 5:00 | Las Vegas, Nevada | Defended UFC Light Heavyweight Championship |
| Win | 9–2 | Vladimir Matyushenko | Decision (Unanimous) | UFC 33: Victory in Vegas | September 28, 2001 | 5 | 5:00 | Las Vegas, Nevada | Defended UFC Light Heavyweight Championship |
| Win | 8–2 | Elvis Sinosic | TKO (Punches and Elbows) | UFC 32: Showdown in the Meadowlands | June 29, 2001 | 1 | 3:32 | East Rutherford, New Jersey | Defended UFC Light Heavyweight Championship |
| Win | 7–2 | Evan Tanner | KO (Slam) | UFC 30: Battle on the Boardwalk | February 23, 2001 | 1 | 0:30 | Atlantic City, New Jersey | Defended UFC Light Heavyweight Championship |
| Win | 6–2 | Yuki Kondo | Submission (Neck Crank) | UFC 29: Defense of the Belts | December 16, 2000 | 1 | 1:51 | Tokyo, Japan | Defended UFC Light Heavyweight Championship |
| Win | 5–2 | Wanderlei Silva | Decision (Unanimous) | UFC 25: Ultimate Japan 3 | April 14, 2000 | 5 | 5:00 | Tokyo, Japan | Won UFC Light Heavyweight Championship |
| Loss | 4–2 | Frank Shamrock | Submission (Strikes) | UFC 22: Only One Can be Champion | September 24, 1999 | 4 | 4:50 | Lake Charles, Louisiana | For UFC Light Heavyweight Championship |
| Win | 4–1 | Guy Mezger | TKO (Strikes) | UFC 19:Ultimate Young Guns | March 5, 1999 | 1 | 9:56 | Bay St. Louis, Mississippi | |
| Win | 3–1 | Jerry Bohlander | TKO (Cut) | UFC 18: Road to the Heavyweight Title | January 8, 1999 | 1 | 14:31 | New Orleans, Louisiana | |
| Win | 2–1 | Jeremy Screeton | Submission (Knees) | West Coast NHB Championships 1 | December 8, 1998 | 1 | 2:27 | | |
| Loss | 1–1 | Guy Mezger | Submission (Guillotine Choke) | UFC 13: The Ultimate Force | May 30, 1997 | 1 | 3:00 | Augusta, Georgia | |
| Win | 1–0 | Wes Albritton | TKO (Strikes) | UFC 13: The Ultimate Force | May 30, 1997 | 1 | 0:31 | Augusta, Georgia | |
