| Fighter | Record | Last Bout |
|---|---|---|
| Jarred Brooks | 13-2-0 | 2018-09-08 |
| Jasmine Jasudavicius | 15-4-0 | 2026-10-17 |
| Jason Black | 23-4-1 | 2007-10-20 |
| Jason Brilz | 22-6-1 | 2011-11-19 |
| Jason Day | 19-12-0 | 2009-03-07 |
| Jason DeLucia | 33-21-1 | 1999-11-19 |
| Jason Dent | 22-13-0 | 2009-11-21 |
| Jason Fairn | 4-5-0 | 1994-12-16 |
| Jason Gilliam | 14-9-0 | 2007-07-07 |
| Jason Godsey | 16-16-0 | 1999-09-24 |
| Jason Gonzalez | 11-5-0 | 2019-04-27 |
| Jason High | 21-6-0 | 2014-06-07 |
| Jason Knight | 20-5-0 | 2018-11-03 |
| Jason Lambert | 26-13-0 | 2008-09-06 |
| Jason MacDonald | 25-16-0 | 2012-05-15 |
| Jason Miller | 23-10-0 (1 NC) | 2012-05-26 |
| Jason Novelli | 11-3-1 | 2016-11-05 |
| Jason Reinhardt | 20-3-0 | 2011-08-14 |
| Jason Saggo | 12-4-0 | 2017-09-16 |
| Jason Tan | 5-3-0 | 2008-05-24 |
| Jason Thacker | 0-1-0 | 2005-04-09 |
| Jason Von Flue | 14-12-1 | 2006-08-17 |
| Jason Witt | 19-9-0 | 2022-08-13 |
| Jason Young | 9-6-0 | 2012-09-29 |
| Javid Basharat | 15-2-0 (1 NC) | 2026-02-07 |
| Javier Reyes | 23-6-0 | 2026-06-27 |
| Javier Vazquez | 16-5-0 | 2011-06-26 |
| Jay Cucciniello | 8-1-0 | 2018-07-06 |
| Jay Hieron | 23-7-0 | 2013-02-02 |
| Jay Perrin | 10-7-0 | 2022-12-10 |
| Jay Silva | 10-11-1 | 2010-01-11 |
| Jean Matsumoto | 18-2-0 | 2026-06-27 |
| Jean Silva | 17-3-0 | 2026-09-12 |
| Jean-Paul Lebosnoyani | 11-2-0 | 2026-07-18 |
| Jeff Cox | 10-7-0 | 2008-04-02 |
| Jeff Curran | 36-18-1 | 2012-05-15 |
| Jeff Hougland | 10-6-0 | 2012-11-10 |
| Jeff Hughes | 10-4-0 (1 NC) | 2020-09-26 |
| Jeff Joslin | 5-3-0 | 2006-12-13 |
| Jeff Molina | 11-2-0 | 2022-06-04 |
| Jeff Monson | 60-26-1 | 2006-11-18 |
| Jeff Newton | 4-2-0 | 2005-11-19 |
| Jefferson Nascimento | 13-1-0 | 2026-06-27 |
| Jeisla Chaves | 8-1-0 | 2026-08-22 |
| Jeka Saragih | 14-5-0 | 2025-06-07 |
| Jenel Lausa | 7-5-0 | 2018-06-23 |
| Jennifer Maia | 21-10-1 | 2023-10-14 |
| Jens Pulver | 27-19-1 | 2007-06-23 |
| JeongYeong Lee | 11-3-0 | 2025-05-10 |
| Jeremiah Wells | 14-4-1 | 2026-08-15 |