| Fighter | Record | Last Bout |
|---|---|---|
| Kamal Shalorus | 9-5-2 | 2012-05-15 |
| Kamaru Usman | 21-5-0 | 2026-07-18 |
| Kamuela Kirk | 12-6-0 | 2023-07-08 |
| Kanako Murata | 12-3-0 | 2023-10-07 |
| Karine Gevorgyan | 3-3-0 | 2017-12-01 |
| Karine Silva | 19-7-0 | 2026-04-18 |
| Karl Roberson | 9-6-0 | 2022-07-09 |
| Karl Williams | 10-2-0 | 2024-08-10 |
| Karlos Vemola | 17-5-0 | 2013-06-08 |
| Karo Parisyan | 24-11-0 (1 NC) | 2010-11-20 |
| Karol Rosa | 19-8-0 | 2026-06-20 |
| Karolina Kowalkiewicz | 16-10-0 | 2025-10-11 |
| Katlyn Cerminara | 18-6-0 | 2026-10-17 |
| Katsuhisa Fujii | 9-18-1 | 1999-11-19 |
| Katsunori Kikuno | 24-8-2 | 2015-09-26 |
| Kaue Fernandes | 11-3-0 | 2026-08-15 |
| Kay Hansen | 7-6-0 | 2022-04-09 |
| Kayla Harrison | 19-1-0 | 2025-06-07 |
| Kaynan Kruschewsky | 15-3-0 (1 NC) | 2024-07-20 |
| 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 Nakamura | 8-1-0 | 2026-01-31 |
| 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 |
| Kelvin Gastelum | 21-11-0 (1 NC) | 2026-04-11 |
| 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 |
| Kennedy Nzechukwu | 14-7-1 | 2026-08-22 |
| 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 |
| Ketlen Souza | 17-6-0 | 2026-06-06 |
| Ketlen Vieira | 16-5-0 | 2026-05-16 |
| Kevin Aguilar | 17-5-0 | 2021-05-15 |
| Kevin Borjas | 11-6-0 | 2026-08-29 |
| Kevin Burns | 12-7-0 | 2009-12-12 |
| Kevin Casey | 9-5-2 (2 NC) | 2016-08-27 |