| Fighter | Record | Last Bout |
|---|---|---|
| Keith Jardine | 17-11-2 | 2010-06-19 |
| Kevin Jackson | 4-2-0 | 1998-03-13 |
| Kevin Jordan | 11-9-0 | 2005-11-19 |
| Krzysztof Jotko | 24-6-0 | 2022-10-01 |
| Lavar Johnson | 18-10-0 | 2013-02-23 |
| Li Jingliang | 19-9-0 | 2024-08-17 |
| Liana Jojua | 8-5-0 | 2021-11-13 |
| Luke Jumeau | 13-5-0 | 2019-10-05 |
| Maciej Jewtuszko | 12-3-0 | 2011-02-26 |
| Marcio Alexandre Junior | 17-4-0 | 2015-12-12 |
| Marcus Jones | 4-2-0 | 2009-12-05 |
| Mike Jackson | 1-2-0 (1 NC) | 2022-10-15 |
| Myles Jury | 17-4-0 | 2019-02-17 |
| Paul Jones | 11-1-1 | 1999-09-24 |
| Phil Johns | 30-14-1 | 2001-02-23 |
| Quinton Jackson | 37-12-0 | 2015-04-25 |
| Ronald Jhun | 24-26-2 | 2004-08-21 |
| Rony Jason | 14-7-0 (1 NC) | 2017-03-11 |
| Ryan Janes | 10-3-0 | 2017-12-01 |
| Ryan Jensen | 21-8-0 | 2011-04-30 |
| Ryan Jimmo | 19-5-0 | 2015-05-30 |
| Scott Jorgensen | 15-12-0 | 2015-11-21 |
| Scott Junk | 8-3-1 (1 NC) | 2007-09-22 |
| Shawn Jordan | 19-8-0 | 2015-10-03 |
| Silvana Gomez Juarez | 11-5-0 | 2022-11-12 |
| Steve Jennum | 2-3-0 | 1995-12-16 |
| Steve Judson | 0-2-0 | 2000-03-10 |
| Sung Bin Jo | 9-1-0 | 2019-06-01 |
| Timothy Johnson | 12-4-0 | 2018-02-03 |
| Trent Jenkins | 0-4-0 | 1995-12-16 |
| Trevin Jones | 13-10-0 (1 NC) | 2023-03-04 |
| Yves Jabouin | 20-11-0 | 2015-08-23 |