| Date | Event | Alternate Name/s | Location | Attendance | PPV Buyrate | Notes |
| January 16 | WEC 9: Cold Blooded | — |  Lemoore, California, United States | — | — | — |
| January 31 | UFC 46: Supernatural | — | Las Vegas, United States | 10,700 | 80,000 | — |
| February 1 | Pride 27: Inferno | — |  Osaka, Japan | 13,366 | — | — |
| February 15 | Pride Bushido 2 | — | Yokohama, Japan | — | — | — |
| March 14 | K-1 Beast 2004 in Niigata | — | Niigata, Japan | — | — | Event featured five K-1 kickboxing bouts, and four K-1 MMA bouts. |
| April 2 | UFC 47: It's On! | — | Las Vegas, Nevada, United States | 11,437 | 105,000 | This event featured a highly anticipated fight between Chuck Liddell and Tito Ortiz. |
| April 25 | Pride Total Elimination 2004 | — | Saitama, Japan | 42,110 | — | Opening round to Pride GP 2004 heavyweight tournament. |
| May 21 | WEC 10: Bragging Rights | — | Lemoore, California, United States | — | — | — |
| May 22 | K-1 MMA ROMANEX | — | Saitama, Japan | 14,918 | — | — |
| May 23 | Pride Bushido 3 | — | Yokohama, Japan | — | — | This event was highlighted by three fights between Team Gracie and Team Japan. |
| June 19 | UFC 48: Payback | — | Las Vegas, Nevada, United States | 10,000 | 110,000 | — |
| June 20 | Pride Critical Countdown 2004 | — | Saitama, Japan | 43,711 | — | Quarterfinals to Pride GP 2004 heavyweight tournament. |
| July 19 | Pride Bushido 4 | — | Nagoya, Japan | — | — | This event was highlighted by three fights between Brazilian Top Team and Team Japan. |
| August 15 | Pride Final Conflict 2004 | — | Saitama, Japan | 47,629 | — | Semifinals and final to Pride GP 2004 heavyweight tournament.
The final between, Fedor Emelianenko and Antônio Rodrigo Nogueira ended in a no contest.
A rematch for the final was rescheduled for Pride Shockwave 2004. |
| August 21 | UFC 49: Unfinished Business | — | Paradise, Nevada, United States | 12,100 | 80,000 | — |
| October 14 | Pride Bushido 5 | — | Osaka, Japan | — | — | — |
| October 21 | WEC 12: Halloween Fury 3 | — | Lemoore, California, United States | — | — | — |
| October 22 | UFC 50: The War of '04 | — | Atlantic City, New Jersey, United States | 9,000 | 40,000 | — |
| October 31 | Pride 28: High Octane | — | Saitama, Japan | 24,028 | — | — |
| November 20 | K-1 Fighting Network Rumble on the Rock 2004 | — | Honolulu, Hawaii, United States | 13,000 | — | — |
| December 31 | Pride Shockwave 2004 | — | Saitama, Japan | 48,398 | — | Fedor Emelianenko becomes the Pride 2004 heavyweight Grand Prix champion. |
| December 31 | K-1 PREMIUM 2004 Dynamite!! | — | Osaka, Japan | 52,918 | — | Event featured seven K-1 MMA bouts, three K-1 kickboxing bouts, and one special mixed rules bout. |
