| Result | Record | Opponent | Method | Event | Date | Round | Time | Location | Notes |
| Loss | 30-10-2 | Yushin Okami | Decision (Unanimous) | UFC 122: Marquardt vs. Okami | November 13, 2010 | 3 | 5:00 | Oberhausen, Germany | To determine the #1 contender for the UFC Middleweight Championship |
| Win | 30-9-2 | Rousimar Palhares | TKO (Punches) | UFC Fight Night: Marquardt vs. Palhares | September 15, 2010 | 1 | 3:28 | Austin, Texas, US | |
| Loss | 29-9-2 | Chael Sonnen | Decision (Unanimous) | UFC 109: Relentless | February 6, 2010 | 3 | 5:00 | Las Vegas, Nevada, US | To determine a #1 Contender for the UFC Middleweight Title; Won Fight of the Night Honors |
| Win | 29–8–2 | Demian Maia | KO (Punch) | UFC 102: Couture vs. Nogueira | August 29, 2009 | 1 | 0:21 | Portland, Oregon, US | Won Knockout of the Night Honors |
| Win | 28–8–2 | Wilson Gouveia | TKO (Strikes) | UFC 95: Sanchez vs. Stevenson | February 21, 2009 | 3 | 3:10 | London, England | |
| Win | 27–8–2 | Martin Kampmann | TKO (Strikes) | UFC 88: Breakthrough | September 6, 2008 | 1 | 1:22 | Atlanta, Georgia, US | |
| Loss | 26–8–2 | Thales Leites | Decision (Split) | UFC 85: Bedlam | June 7, 2008 | 3 | 5:00 | London, England | Nate was Docked 1 point in round 2 for kneeing a downed opponent & 1 point in round 3 for strikes to the back of the head. |
| Win | 26–7–2 | Jeremy Horn | Submission (Guillotine Choke) | UFC 81: Breaking Point | February 2, 2008 | 2 | 1:37 | Las Vegas, Nevada, US | |
| Loss | 25–7–2 | Anderson Silva | TKO (Punches) | UFC 73: Stacked | July 7, 2007 | 1 | 4:50 | Sacramento, California, US | For UFC Middleweight Championship |
| Win | 25–6–2 | Dean Lister | Decision (Unanimous) | Ultimate Fight Night 8 | January 25, 2007 | 3 | 5:00 | Hollywood, Florida, US | |
| Win | 24–6–2 | Crafton Wallace | Submission (Rear Naked Choke) | Ortiz vs. Shamrock 3: The Final Chapter | October 10, 2006 | 2 | 1:14 | Hollywood, Florida, US | |
| Win | 23–6–2 | Joe Doerksen | Decision (Unanimous) | UFC 58: USA vs Canada | March 4, 2006 | 3 | 5:00 | Las Vegas, Nevada, US | |
| Win | 22–6–2 | Ivan Salaverry | Decision (Unanimous) | Ultimate Fight Night | August 6, 2005 | 3 | 5:00 | Las Vegas, Nevada, US | |
| Win | 21–6–2 | Izuru Takeuchi | Technical Submission (Rear Naked Choke) | Pancrase – Spiral 4 | May 1, 2005 | 3 | 2:19 | Yokohama, Japan | Defended King of Pancrase Middleweight Championship; Vacated title post-fight |
| Win | 20–6–2 | Kazuo Misaki | Decision (Unanimous) | Pancrase – Brave 10 | November 7, 2004 | 3 | 5:00 | Tokyo, Japan | Won King of Pancrase Middleweight Championship |
| Draw | 19–6–2 | Eiji Ishikawa | Draw | Pancrase – Brave 6 | June 22, 2004 | 3 | 5:00 | Tokyo, Japan | |
| Loss | 19–6–1 | Ricardo Almeida | Submission (Guillotine Choke) | Pancrase – Hybrid 10 | November 30, 2003 | 1 | 4:53 | Tokyo, Japan | Lost King of Pancrase Middleweight Championship |
| Win | 19–5–1 | Yuji Hisamatsu | Decision (Unanimous) | Pancrase – Hybrid 8 | October 4, 2003 | 2 | 5:00 | Osaka, Japan | |
| Win | 18–5–1 | Steve Gomm | Submission (Punches) | IFC – Global Domination | September 6, 2003 | 1 | 3:28 | Denver, Colorado, US | |
| Loss | 17–5–1 | Keiichiro Yamamiya | Decision (Unanimous) | Pancrase – 2003 Neo-Blood Tournament, Round 2 | July 27, 2003 | 3 | 5:00 | Tokyo, Japan | |
| Win | 17–4–1 | Izuru Takeuchi | KO (Punches) | Pancrase – Hybrid 3 | March 8, 2003 | 1 | 1:29 | Tokyo, Japan | Defended King of Pancrase Middleweight Championship |
| Win | 16–4–1 | Kiuma Kunioku | KO (Flying Knee) | Pancrase – Spirit 9 | December 21, 2002 | 3 | 4:36 | Tokyo, Japan | Won King of Pancrase Middleweight Championship |
| Loss | 15–4–1 | Izuru Takeuchi | Decision (Unanimous) | Pancrase – Spirit 7 | October 29, 2002 | 3 | 5:00 | Tokyo, Japan | |
| Win | 15–3–1 | Seiki Ryo | Technical Submission (Armbar) | Pancrase – 2002 Neo-Blood Tournament, Round 2 | July 28, 2002 | 1 | 1:37 | Tokyo, Japan | |
| Win | 14–3–1 | Kazuo Misaki | TKO (Broken Arm) | Pancrase – Spirit 3 | March 25, 2002 | 1 | 0:29 | Tokyo, Japan | |
| Loss | 13–3–1 | Kiuma Kunioku | Decision (Majority) | Pancrase – Proof 7 | December 1, 2001 | 3 | 5:00 | Yokohama, Japan | Lost King of Pancrase Middleweight Championship |
| Win | 13–2–1 | Yuji Hoshino | Submission (Triangle Choke) | Pancrase – Proof 6 | October 30, 2001 | 3 | 2:13 | Tokyo, Japan | Defended King of Pancrase Middleweight Championship |
| Loss | 12–2–1 | Gil Castillo | Decision (Unanimous) | IFC WC 14 – Warriors Challenge 14 | July 18, 2001 | 5 | 5:00 | California, US | |
| Win | 12–1–1 | Masaya Kojima | Submission (Armbar) | Pancrase – Proof 3 | May 13, 2001 | 1 | 1:45 | Tokyo, Japan | |
| Win | 11–1–1 | Hikaru Sato | Submission (Rear Naked Choke) | Pancrase – Proof 2 | March 31, 2001 | 1 | 1:53 | Osaka, Japan | |
| Draw | 10–1–1 | Kiuma Kunioku | Draw | Pancrase – Trans 7 | December 4, 2000 | 1 | 20:00 | Tokyo, Japan | Defended King of Pancrase Middleweight Championship |
| Win | 10–1 | Kiuma Kunioku | Decision (Unanimous) | Pancrase – 2000 Anniversary Show | September 24, 2000 | 1 | 10:00 | Yokohama, Japan | Won King of Pancrase Middleweight Championship; First in Pancrase |
| Win | 9–1 | Shonie Carter | Decision (Unanimous) | Pancrase – 2000 Anniversary Show | September 24, 2000 | 2 | 3:00 | Yokohama, Japan | |
| Win | 8–1 | Daiju Takase | KO (Knee) | Pancrase – Trans 4 | June 26, 2000 | 2 | 1:30 | Tokyo, Japan | |
| Win | 7–1 | Anthony Washington | Submission (Strikes) | ROF 1 – Ring of Fire 1 | March 18, 2000 | N/A | | Denver, Colorado, US | |
| Loss | 6–1 | Genki Sudo | Submission (Armbar) | Pancrase – Breakthrough 11 | December 18, 1999 | 1 | 13:31 | Yokohama, Japan | |
| Win | 6–0 | David Harris | Submission (Rear Naked Choke) | BRI 4 – Bas Rutten Invitational 4 | August 14, 1999 | 1 | 15:01 | | |
| Win | 5–0 | Josh Groves | Submission (Triangle Choke) | BRI 4 – Bas Rutten Invitational 4 | August 14, 1999 | 1 | 1:49 | | |
| Win | 4–0 | Yves Edwards | Submission (Heel Hook) | BRI 4 – Bas Rutten Invitational 4 | August 14, 1999 | 1 | 3:04 | | |
| Win | 3–0 | Jose Garcia | Submission | RITR – Rumble in the Rockies | June 7, 1999 | 1 | 3:32 | Denver, Colorado, US | |
| Win | 2–0 | Josh Medina | Submission (Choke) | RITR – Rumble in the Rockies | June 7, 1999 | 1 | 0:27 | Denver, Colorado, US | |
| Win | 1–0 | Mike Lee | Submission | WVF – Durango | April 17, 1999 | 2 | 2:13 | Durango, Colorado, US | |
