| Fighter | Record | Last Bout |
|---|---|---|
| Kazuhiro Nakamura | 21-13-0 | 2008-05-24 |
| Kazuki Tokudome | 18-7-1 | 2014-09-20 |
| Kazula Vargas | 12-5-0 | 2022-03-19 |
| Kazushi Sakuraba | 26-17-1 (2 NC) | 1997-12-21 |
| Keigo Kunihara | 3-2-0 | 2005-10-07 |
| Keiichiro Yamamiya | 45-35-10 | 1999-11-19 |
| Keita Nakamura | 34-10-2 (1 NC) | 2019-04-20 |
| Keith Berish | 5-1-0 (1 NC) | 2016-12-09 |
| Keith Hackney | 2-2-0 | 1995-12-16 |
| Keith Jardine | 17-11-2 | 2010-06-19 |
| Keith Mielke | 0-5-0 | 1996-02-16 |
| Keith Rockel | 12-4-1 | 2003-11-21 |
| Keith Wisniewski | 28-15-1 | 2013-09-04 |
| Kelly Dullanty | 4-2-0 | 2002-03-22 |
| Kelly Faszholz | 4-2-0 | 2016-10-01 |
| Ken Shamrock | 28-17-2 | 2006-10-10 |
| Ken Stone | 11-4-0 | 2012-08-11 |
| Kendall Grove | 23-17-0 (1 NC) | 2011-05-28 |
| Kenichi Yamamoto | 5-12-2 | 2000-12-16 |
| Kenny Florian | 14-6-0 | 2011-10-08 |
| Kenny Robertson | 15-5-0 | 2016-09-17 |
| Kerry Schall | 24-13-0 (1 NC) | 2005-11-05 |
| Kevin Aguilar | 17-5-0 | 2021-05-15 |
| Kevin Burns | 12-7-0 | 2009-12-12 |
| Kevin Casey | 9-5-2 (2 NC) | 2016-08-27 |
| Kevin Croom | 21-15-0 (1 NC) | 2022-04-16 |
| Kevin Ferguson | 5-2-0 (1 NC) | 2010-05-08 |
| Kevin Jackson | 4-2-0 | 1998-03-13 |
| Kevin Jordan | 11-9-0 | 2005-11-19 |
| Kevin Lee | 18-8-0 | 2023-07-01 |
| Kevin Natividad | 9-4-0 | 2022-11-19 |
| Kevin Randleman | 17-16-0 | 2002-01-11 |
| Kevin Rosier | 2-6-0 | 1994-12-16 |
| Khabib Nurmagomedov | 29-0-0 | 2020-10-24 |
| Khadis Ibragimov | 8-4-0 | 2020-09-26 |
| Khalid Murtazaliev | 14-2-0 | 2018-09-15 |
| Khalid Taha | 13-5-0 (1 NC) | 2022-09-03 |
| Khama Worthy | 16-9-0 | 2021-10-23 |
| Khusein Askhabov | 23-1-0 | 2023-02-18 |
| Kiichi Kunimoto | 18-7-2 (1 NC) | 2017-06-10 |
| Kimo Leopoldo | 10-7-1 | 2004-06-19 |
| Kit Cope | 6-7-0 | 2005-11-05 |
| Kleydson Rodrigues | 8-4-0 | 2024-05-18 |
| Klidson Abreu | 15-4-0 (1 NC) | 2020-05-30 |
| Koji Kitao | 1-2-0 | 1996-05-17 |
| Koji Oishi | 25-10-10 | 2005-06-04 |
| Konstantin Erokhin | 9-3-0 | 2015-12-11 |
| Kris McCray | 8-5-0 | 2011-03-26 |
| Kristian Rothaermel | 4-3-0 | 2006-06-28 |
| Kristof Midoux | 6-10-0 | 2006-08-17 |