| Fighter | Record | Last Bout |
|---|---|---|
| Isabela de Padua | 5-2-0 | 2019-11-16 |
| Islam Dulatov | 12-1-0 | 2025-07-19 |
| Islam Makhachev | 29-1-0 | 2026-08-15 |
| Ismael Bonfim | 20-7-0 | 2026-07-25 |
| Ismail Naurdiev | 25-8-0 | 2026-10-03 |
| Israel Adesanya | 24-6-0 | 2026-03-28 |
| Issei Tamura | 10-8-0 | 2013-03-16 |
| Istela Nunes | 6-6-0 (1 NC) | 2025-04-05 |
| Iuri Alcantara | 35-10-0 (1 NC) | 2018-08-25 |
| Ivan Erslan | 15-6-0 (1 NC) | 2026-05-16 |
| Ivan Jorge | 27-7-0 | 2015-07-18 |
| Ivan Menjivar | 25-12-0 | 2014-03-01 |
| Ivan Salaverry | 14-9-0 | 2008-05-24 |
| Ivan Serati | 12-4-0 | 2009-01-17 |
| Ivana Petrovic | 7-3-0 | 2025-05-03 |
| Iwo Baraniewski | 9-0-0 | 2026-09-19 |
| Izabela Badurek | 6-3-0 | 2015-04-11 |
| Jacare Souza | 26-10-0 (1 NC) | 2021-05-15 |
| Jack Della Maddalena | 18-4-0 | 2026-05-02 |
| Jack Hermansson | 24-10-0 | 2025-11-22 |
| Jack Jenkins | 14-5-0 | 2026-08-29 |
| Jack Marshman | 23-10-0 | 2020-10-31 |
| Jack May | 9-3-0 | 2014-08-16 |
| Jack McGlaughlin | 1-4-0 | 1995-07-14 |
| Jack Nilson | 2-6-0 | 1997-05-30 |
| Jack Shore | 17-3-0 | 2024-11-02 |
| Jackie Lee | 0-1-0 | 1997-02-07 |
| Jackson McVey | 8-2-0 | 2026-08-22 |
| Jacob Kilburn | 8-4-0 | 2021-01-16 |
| Jacob Malkoun | 10-3-0 | 2026-05-02 |
| Jacob Volkmann | 19-7-0 | 2013-02-02 |
| Jacobe Smith | 12-0-0 | 2026-02-21 |
| Jacqueline Cavalcanti | 10-2-0 | 2026-05-16 |
| Jafel Filho | 17-5-0 | 2026-04-25 |
| Jai Herbert | 14-6-1 | 2026-04-18 |
| Jailton Almeida | 22-5-0 | 2026-02-07 |
| Jairzinho Rozenstruik | 15-6-0 | 2025-02-01 |
| Jake Collier | 13-10-0 | 2023-09-23 |
| Jake Ellenberger | 31-15-0 | 2018-08-25 |
| Jake Hadley | 11-4-0 | 2024-10-19 |
| Jake Hecht | 11-4-0 | 2012-06-08 |
| Jake Lindsey | 12-7-0 | 2015-03-14 |
| Jake Matthews | 23-8-0 | 2026-05-30 |
| Jake O'Brien | 15-4-0 | 2009-07-11 |
| Jake Rosholt | 12-5-0 (1 NC) | 2009-11-21 |
| Jake Shields | 31-9-1 (1 NC) | 2014-03-15 |
| Jakub Wiklacz | 18-3-2 | 2026-02-07 |
| Jalin Turner | 16-9-0 | 2026-08-15 |
| Jamahal Hill | 12-4-0 (1 NC) | 2025-06-21 |
| Jamal Pogues | 11-5-0 | 2025-02-01 |