2005 in sports describes the year's events in world sport.
Men's professional
Men's amateur
Women's professional
Steeplechases
Flat races
Major League Lacrosse (USA)
NCAA Division I (US Collegiate)
European lacrosse
The following is a list of major noteworthy MMA events during 2005 in chronological order.
| Date | Event | Alternate Name/s | Location | Attendance | PPV Buyrate | Notes |
| February 5 | UFC 51: Super Saturday | — |  Las Vegas, Nevada, USA | 11,072 | 105,000 | This event was originally going to be held in Japan. However was moved it back toLas Vegas. |
| February 20 | Pride 29: Fists of Fire | — |  Saitama, Japan | 22,047 | — | — |
| March 26 | K-1 Hero's 1 | — | Saitama, Japan | — | — | K-1 Hero's first event. |
| April 3 | Pride Bushido 6 | — | Yokohama, Japan | — | — | — |
| April 9 | The Ultimate Fighter 1 Finale | — | Las Vegas, Nevada, USA | — | — | This event is credited for saving the UFC from bankruptcy and launching the MMA into the mainstream American media. |
| April 16 | UFC 52: Couture vs. Liddell 2 | — | Las Vegas, Nevada, USA | 14,562 | 280,000 | Dan "The Beast" Severn was inducted into the UFC Hall of Fame at this event. |
| April 23 | Pride Total Elimination 2005 | — | Osaka, Japan | 45,423 | — | Opening round to Pride GP 2005 middleweight tournament. |
| May 7 | Rumble on the Rock 7 | — | Honolulu, Hawaii, USA | — | — | — |
| May 22 | Pride Bushido 7 | — | Tokyo, Japan | — | — | — |
| June 4 | UFC 53: Heavy Hitters | — | Atlantic City, New Jersey, USA | 12,000 | 90,000 | This event was originally going to be held inYokohama. However the lack of a sponsorship for the event moved it toAtlantic City. |
| June 26 | Pride Critical Countdown 2005 | — | Saitama, Japan | — | — | Quarterfinals to Pride GP 2005 middleweight tournament. |
| July 6 | K-1 Hero's 2 | — | Tokyo, Japan | — | — | — |
| July 17 | Pride Bushido 8 | — | Nagoya, Japan | — | — | — |
| July 29 | K-1 World Grand Prix 2005 in Hawaii | — | Honolulu, Hawaii, USA | — | — | Event featured tenK-1 kickboxing bouts and four K-1 MMA bouts. |
| August 6 | UFC Ultimate Fight Night | Ultimate Fight Night | Las Vegas, Nevada, USA | — | — | — |
| August 20 | UFC 54: Boiling Point | — | Las Vegas, Nevada, USA | 13,520 | 150,000 | — |
| August 28 | Pride Final Conflict 2005 | — | Saitama, Japan | — | — | Semifinals and final to Pride GP 2005 middleweight tournament. Maurício Rua becomes the Pride 2005 middleweight Grand Prix champion. |
| September 7 | K-1 Hero's 3 | — | Tokyo, Japan | — | — | — |
| September 25 | Pride Bushido 9 | — | Tokyo, Japan | 10,775 | — | Quarterfinals and semifinals to Pride GP 2005 lightweight and welterweight tournaments. |
| October 3 | UFC Ultimate Fight Night 2 | Ultimate Fight Night 2 | Las Vegas, Nevada, USA | — | — | This event was aired at the same timeWWE was on, in a ratings battle. |
| October 3 | UFC 55: Fury | — | Uncasville, Connecticut, USA | 8,000 | 125,000 | — |
| October 3 | Pride 30: Starting Over | Pride 30: Fully Loaded | Saitama, Japan | — | — | — |
| November 5 | The Ultimate Fighter 2 Finale | — | Las Vegas, Nevada, USA | — | — | — |
| November 5 | K-1 Seoul Hero's | — |  Seoul, South Korea | — | — | — |
| November 19 | UFC 56: Full Force | — | Las Vegas, Nevada, USA | 12,000 | 200,000 | — |
| November 26 | K-1 Hero's Lithuania 2005 | — |  Vilnius, Lithuania | — | — | — |
| December 3 | Cage Rage 14: Punishment | — |  London, England | — | — | — |
| December 3 | Pride Shockwave 2005 | — | Saitama, Japan | 49,801 | — | Finals to Pride GP 2005 lightweight and welterweight tournaments. Takanori Gomi becomes the Pride 2005 lightweight Grand Prix champion. Dan Henderson becomes the Pride 2005 welterweight Grand Prix champion. |
| December 3 | K-1 PREMIUM 2005 Dynamite!! | — | Osaka, Japan | 53,025 | — | Event featured sevenK-1 Hero's MMA bouts and fourK-1 kickboxing bouts. |