| Fighter | Record | Last Bout |
|---|---|---|
| Roman Bogatov | 10-1-0 | 2020-07-11 |
| Roman Dolidze | 15-6-0 | 2026-08-22 |
| Roman Kopylov | 15-5-0 | 2026-10-03 |
| Roman Mitichyan | 8-3-0 | 2008-04-02 |
| Roman Salazar | 10-6-0 (1 NC) | 2015-08-08 |
| Romie Aram | 7-1-0 | 2003-04-25 |
| Ron Faircloth | 33-20-0 (1 NC) | 2005-10-07 |
| Ron Stallings | 14-8-0 (1 NC) | 2015-09-05 |
| Ron van Clief | 0-1-0 | 1994-12-16 |
| Ron Waterman | 16-6-2 | 2000-04-14 |
| Ronald Jhun | 24-26-2 | 2004-08-21 |
| Ronaldo Rodriguez | 17-3-0 | 2025-03-29 |
| Ronda Rousey | 12-2-0 | 2016-12-30 |
| Rongzhu | 28-6-0 | 2026-09-12 |
| Ronnie Lawrence | 8-2-0 (1 NC) | 2023-06-17 |
| Ronny Markes | 17-5-0 | 2014-03-23 |
| Rony Jason | 14-7-0 (1 NC) | 2017-03-11 |
| Ronys Torres | 35-5-0 | 2010-03-31 |
| Roosevelt Roberts | 12-6-0 (1 NC) | 2024-09-28 |
| Roque Martinez | 15-8-2 | 2021-06-19 |
| Rory MacDonald | 19-4-0 | 2016-06-18 |
| Rory Markham | 17-6-0 | 2010-03-27 |
| Rory Singer | 11-9-0 | 2007-06-16 |
| Rose Namajunas | 15-8-0 | 2026-01-24 |
| Rosi Sexton | 13-5-0 | 2013-10-26 |
| Ross Pearson | 20-16-0 (1 NC) | 2019-03-30 |
| Ross Pointon | 6-17-0 | 2007-01-25 |
| Rostem Akman | 6-2-0 | 2019-10-05 |
| Rousimar Palhares | 19-8-0 | 2013-10-09 |
| Roxanne Modafferi | 25-21-0 | 2022-02-12 |
| Roy Nelson | 22-14-0 | 2017-04-15 |
| Royce Alger | 3-2-0 | 1999-07-16 |
| Royce Gracie | 15-2-3 | 2006-05-27 |
| Royston Wee | 4-1-0 | 2015-05-16 |
| Ruan Potts | 11-6-0 | 2015-02-28 |
| Rudyard Moncayo | 0-3-0 | 1995-07-14 |
| Ruslan Magomedov | 14-1-0 | 2015-10-03 |
| Russell Doane | 15-8-0 | 2018-02-24 |
| Rustam Khabilov | 24-4-0 | 2019-11-09 |
| Ryan Bader | 23-5-0 | 2016-11-19 |
| Ryan Benoit | 10-8-0 | 2021-07-31 |
| Ryan Couture | 11-5-0 | 2013-08-31 |
| Ryan Gandra | 10-1-0 | 2026-09-19 |
| Ryan Hall | 9-2-0 | 2021-12-11 |
| Ryan Janes | 10-3-0 | 2017-12-01 |
| Ryan Jensen | 21-8-0 | 2011-04-30 |
| Ryan Jimmo | 19-5-0 | 2015-05-30 |
| Ryan Kuse | 9-3-0 | 2026-08-22 |
| Ryan LaFlare | 14-3-0 | 2018-10-06 |
| Ryan Loder | 8-3-0 | 2025-11-22 |