| Benji Radach (inactive) | Razor | 1-1-0 (1 NC) | United States | Sep 27, 2002 |
| Jordan Radev (inactive) | | 0-2-0 | Bulgaria | Dec 29, 2007 |
| Charles Radtke | Chuck Buffalo | 5-2-0 | United States | Apr 11, 2026 |
| Loik Radzhabov (inactive) | The Tajik Tank | 2-2-0 | Tajikistan | Jul 20, 2024 |
| Josh Rafferty (inactive) | | 0-1-0 | Unknown | Apr 9, 2005 |
| Marwan Rahiki | Freaky | 2-1-0 | Morocco | Sep 12, 2026 |
| Ricky Rainey (inactive) | The Sniper | 0-2-0 | United States | Nov 30, 2018 |
| Shavkat Rakhmonov | Nomad | 7-0-0 | Uzbekistan | Dec 7, 2024 |
| Aleksandar Rakic | Rocket | 7-5-0 | Austria | Aug 1, 2026 |
| Jessica Rakoczy (inactive) | The Ragin' | 0-2-0 | United States | Apr 25, 2015 |
| Zygimantas Ramaska (inactive) | | 0-1-0 | Lithuania | Sep 7, 2024 |
| Hector Ramirez (inactive) | Sick Dog | 0-2-0 | United States | Jun 16, 2007 |
| Mitch Ramirez | | 0-3-0 | United States | Jul 18, 2026 |
| Thomas Ramirez (inactive) | | 0-1-0 | United States | Feb 16, 1996 |
| Davi Ramos (inactive) | Tasmanian Devil | 4-3-0 | Brazil | Jul 18, 2020 |
| Luis Ramos (inactive) | Beicao | 0-2-0 | Brazil | Jun 22, 2012 |
| Ricardo Ramos (inactive) | | 8-7-0 | Brazil | Oct 11, 2025 |
| Germaine de Randamie (inactive) | The Iron Lady | 7-3-0 | Netherlands | Apr 6, 2024 |
| Kevin Randleman (inactive) | The Monster | 4-3-0 | United States | Jan 11, 2002 |
| Mitch Raposo | | 2-2-0 | United States | Jun 20, 2026 |
| Bec Rawlings (inactive) | Rowdy | 2-5-0 | Australia | Apr 7, 2018 |
| Gideon Ray (inactive) | | 0-3-0 | United States | Nov 11, 2006 |
| Stevie Ray (inactive) | Braveheart | 7-4-0 | United Kingdom | Oct 26, 2019 |
| Mateusz Rebecki | | 5-4-0 | Poland | Aug 1, 2026 |
| Paul Redmond (inactive) | Redser | 0-2-0 | United States | Jul 18, 2015 |
| Elise Reed | | 4-6-0 | United States | Aug 22, 2026 |
| Johnny Rees (inactive) | The Hater Hurter | 0-2-0 | United States | Dec 10, 2008 |
| Zach Reese | Savage | 4-4-0 (1 NC) | United States | Jul 11, 2026 |
| Chad Reiner (inactive) | The Grinder | 0-2-0 | United States | Jun 12, 2007 |
| Jason Reinhardt (inactive) | | 0-3-0 | United States | Aug 14, 2011 |
| Wilson Reis (inactive) | | 7-6-0 | Brazil | Apr 13, 2019 |
| Goran Reljic (inactive) | | 1-3-0 | Croatia | Nov 13, 2010 |
| Leigh Remedios (inactive) | Bulldog | 0-1-0 | United Kingdom | Jul 13, 2002 |
| Chance Rencountre (inactive) | Black Eagle | 2-2-0 | United States | Nov 2, 2019 |
| Montse Rendon (inactive) | Monster | 2-2-0 | Mexico | Mar 14, 2026 |
| Marion Reneau (inactive) | The Belizean Bruiser | 5-7-1 | United States | Jul 17, 2021 |
| Alex Reyes | The Executioner | 0-3-0 | United States | Aug 17, 2024 |
| Dominick Reyes | The Devastator | 10-5-0 | United States | Apr 11, 2026 |
| Javier Reyes | Blair | 1-1-0 | Colombia | Jun 27, 2026 |
| Jon Delos Reyes (inactive) | The Heat | 1-3-0 | Guam | Oct 24, 2015 |
| Marco Polo Reyes (inactive) | | 4-4-0 | Mexico | Sep 21, 2019 |
| Johnny Rhodes (inactive) | | 2-1-0 | United States | Mar 11, 1994 |
| Mike Rhodes (inactive) | Biggie | 0-3-0 | United States | Dec 20, 2014 |
| Amanda Ribas | | 7-6-0 | Brazil | Jul 26, 2025 |
| Brendson Ribeiro | The Gorilla | 2-6-0 | Brazil | Jul 25, 2026 |
| Claudio Ribeiro (inactive) | | 1-3-0 | Brazil | Mar 2, 2024 |
| Esteban Ribovics | El Gringo | 6-3-0 | Argentina | Oct 3, 2026 |
| Alex Ricci (inactive) | | 0-2-0 | Canada | Feb 19, 2017 |
| Mike Ricci (inactive) | The Martian | 1-2-0 | Unknown | Sep 21, 2013 |
| Tabatha Ricci | Baby Shark | 7-5-0 | Brazil | Jul 18, 2026 |
| Brad Riddell (inactive) | Quake | 4-3-0 | New Zealand | Nov 12, 2022 |
| Reinier de Ridder | RdR | 5-2-0 | Netherlands | Aug 22, 2026 |
| Matthew Riddle (inactive) | Deep Waters | 7-3-0 (2 NC) | United States | Feb 16, 2013 |
| Joe Riggs (inactive) | Diesel | 5-7-0 | United States | Feb 21, 2016 |
| Aaron Riley (inactive) | | 3-6-0 | United States | Jul 27, 2013 |
| Luke Riley | | 3-0-0 | United Kingdom | Jul 11, 2026 |
| Jordan Rinaldi (inactive) | All Day | 2-3-0 | United States | Mar 16, 2019 |
| Nick Ring (inactive) | The Promise | 3-3-0 | United States | Dec 6, 2013 |
| Mike Rio (inactive) | The Wolverine | 1-3-0 | United States | Jan 25, 2014 |
| Diego Rivas (inactive) | Pitbull | 2-2-0 | Chile | May 19, 2018 |
| Dante Rivera (inactive) | | 0-1-0 | United States | Jun 21, 2008 |
| Francisco Rivera (inactive) | Cisco | 4-6-0 (1 NC) | United States | Jul 30, 2016 |
| Irwin Rivera (inactive) | The Beast | 1-2-0 | Mexico | Sep 19, 2020 |
| Jerome Rivera (inactive) | Renegade | 0-4-0 | United States | Jul 10, 2021 |
| Jimmie Rivera (inactive) | El Terror | 7-4-0 | United States | Feb 27, 2021 |
| Jorge Rivera (inactive) | El Conquistador | 8-7-0 | United States | Jan 20, 2012 |
| Pedro Rizzo (inactive) | The Rock | 9-5-0 | Brazil | Nov 21, 2003 |
| Karl Roberson (inactive) | Baby K | 4-6-0 | United States | Jul 9, 2022 |
| Andre Roberts (inactive) | The Chief | 2-1-0 | United States | Jul 16, 1999 |
| Buddy Roberts (inactive) | | 1-1-0 | United States | Aug 11, 2012 |
| Daniel Roberts (inactive) | Ninja | 3-4-0 | United States | Jan 20, 2012 |
| Danny Roberts (inactive) | Hot Chocolate | 7-7-0 | United Kingdom | Jul 22, 2023 |
| David Roberts (inactive) | | 0-1-0 | Unknown | May 7, 1999 |
| Joey Roberts (inactive) | | 0-1-0 | Unknown | Mar 5, 1999 |
| Roosevelt Roberts (inactive) | The Predator | 4-5-0 (1 NC) | United States | Sep 28, 2024 |
| Ryan Roberts (inactive) | | 0-1-0 | Unknown | Apr 2, 2008 |
| Tyrone Roberts (inactive) | Native Warrior | 1-0-0 | Unknown | Jun 9, 2000 |
| Gillian Robertson | The Savage | 14-7-0 | Canada | Aug 15, 2026 |
| Kenny Robertson (inactive) | | 4-5-0 | United States | Sep 17, 2016 |
| Alvin Robinson (inactive) | | 1-3-0 | United States | Nov 15, 2008 |
| Colin Robinson (inactive) | Big C | 0-2-0 | Unknown | Jan 19, 2008 |
| Mark Robinson (inactive) | White Rhino | 0-0-0 (1 NC) | South Africa | Feb 23, 2001 |
| Carlos Eduardo Rocha (inactive) | Ta Danado | 1-2-0 | Brazil | Jun 8, 2012 |
| Chris de la Rocha (inactive) | | 1-3-0 | United States | Dec 15, 2018 |
| Lucas Rocha | Fenomeno | 1-1-0 | Brazil | Oct 11, 2025 |
| Vagner Rocha | Ceara | 1-3-0 | United States | Nov 7, 2014 |
| Shem Rock (inactive) | | 0-2-0 | United Kingdom | Mar 21, 2026 |
| Keith Rockel (inactive) | Rock | 1-1-0 | United States | Nov 21, 2003 |
| Luke Rockhold (inactive) | | 6-5-0 | Unknown | Aug 20, 2022 |
| Gregory Rodrigues | Robocop | 11-3-0 | Brazil | Aug 22, 2026 |
| Kleydson Rodrigues (inactive) | KR | 1-3-0 | Brazil | May 18, 2024 |
| Christian Rodriguez | Ceerod | 6-4-0 | United States | Jun 20, 2026 |
| Daniel Rodriguez | D-Rod | 10-5-0 | United States | Aug 1, 2026 |
| Drako Rodriguez (inactive) | | 0-2-0 | United States | Aug 7, 2021 |
| Imanol Rodriguez | Himan | 2-0-0 | Mexico | Oct 3, 2026 |
| Manuel Rodriguez (inactive) | Chalate | 0-1-0 | Unknown | Dec 14, 2012 |
| Marina Rodriguez (inactive) | | 7-6-2 | Brazil | May 3, 2025 |
| Mike Rodriguez (inactive) | Slo Mike | 2-5-0 (1 NC) | United States | Sep 18, 2021 |
| Paul Rodriguez (inactive) | | 0-1-0 | United States | Jun 29, 2001 |
| Pete Rodriguez (inactive) | Dead Game | 1-2-0 | United States | Feb 3, 2024 |
| Piera Rodriguez | La Fiera | 5-2-0 | Venezuela | Mar 14, 2026 |
| Ray Rodriguez (inactive) | The Judge | 0-2-0 | United States | Mar 13, 2021 |
| Ricco Rodriguez (inactive) | Suave | 5-2-0 | United States | Nov 21, 2003 |
| Ronaldo Rodriguez (inactive) | Lazy Boy | 2-1-0 | Unknown | Mar 29, 2025 |
| Victor Rodriguez (inactive) | Vicious | 0-2-0 | Mexico | May 22, 2021 |
| Yair Rodriguez | El Pantera | 11-4-0 (1 NC) | Mexico | Apr 12, 2025 |
| Nick Roehrick (inactive) | | 0-1-0 | United States | Jul 7, 2017 |
| Max Rohskopf (inactive) | Rated R | 0-1-0 | United States | Jun 20, 2020 |
| Nilson Rojas | El Rayo | 0-1-0 | Peru | Aug 29, 2026 |
| Marcelo Rojo (inactive) | Pitbull | 0-3-0 | Argentina | Dec 3, 2022 |
| Shane Roller (inactive) | | 2-4-0 | United States | Oct 5, 2012 |
| Jared Rollins (inactive) | J-Roc | 0-1-0 | United States | Dec 8, 2007 |
| Alexandr Romanov (inactive) | King Kong | 7-3-0 | Moldova | Nov 2, 2024 |
| Anthony Romero | The Bully | 0-1-0 | United States | Oct 3, 2026 |
| Ricardo Romero (inactive) | | 1-2-0 | United States | Sep 24, 2011 |
| Roberto Romero | El Charro Negro | 0-2-0 | Mexico | Apr 26, 2025 |
| Yoel Romero (inactive) | Soldier of God | 9-4-0 | Cuba | Mar 7, 2020 |
| Cortavious Romious (inactive) | | 0-2-0 | United States | Apr 5, 2025 |
| Juancamilo Ronderos | 100 | 0-2-0 | Colombia | Feb 18, 2023 |
| Rongzhu | | 4-3-0 | China | Sep 12, 2026 |
| Jesse Ronson (inactive) | The Body Snatcher | 0-5-0 (1 NC) | Canada | Oct 1, 2022 |
| George Roop (inactive) | | 5-8-0 | United States | Sep 26, 2015 |
| Joao Roque (inactive) | | 0-1-0 | United States | Jun 9, 2000 |
| Aaron Rosa (inactive) | | 1-2-0 | United States | Mar 2, 2012 |
| Charles Rosa | Boston Strong | 5-8-0 | United States | Jul 23, 2022 |
| Karol Rosa | | 8-5-0 | Brazil | Jun 20, 2026 |
| Mark De La Rosa (inactive) | Bumblebee | 2-5-0 | United States | Jun 13, 2020 |
| Montana De La Rosa (inactive) | | 6-5-1 | United States | Jun 8, 2024 |
| Shane del Rosario (inactive) | | 0-2-0 | United States | Dec 15, 2012 |
| Jessie Rosas | Tachidito | 0-1-0 | United States | Sep 12, 2026 |
| Jake Rosholt (inactive) | | 1-2-0 | United States | Nov 21, 2009 |
| Jared Rosholt (inactive) | | 6-2-0 | United States | Feb 6, 2016 |
| Kevin Rosier (inactive) | | 0-1-0 | United States | Dec 16, 1994 |
| Shannon Ross | The Turkish Delight | 0-3-0 | Australia | Dec 9, 2023 |
| Kristian Rothaermel (inactive) | | 0-1-0 | United States | Jun 28, 2006 |
| Ben Rothwell (inactive) | | 9-8-0 | United States | Nov 13, 2021 |
| Ronda Rousey (inactive) | Rowdy | 6-2-0 | Unknown | Dec 30, 2016 |
| Phil Rowe (inactive) | The Fresh Prince | 4-5-0 | United States | Feb 21, 2026 |
| Cam Rowston | | 3-0-0 | Australia | May 2, 2026 |
| Brandon Royval | Raw Dawg | 8-5-0 | United States | Jul 11, 2026 |
| Jairzinho Rozenstruik (inactive) | Bigi Boy | 9-6-0 | Suriname | Feb 1, 2025 |
| Mauricio Rua (inactive) | Shogun | 11-12-1 | Brazil | Jan 21, 2023 |
| Marco Ruas (inactive) | King of the Streets | 4-2-0 | Brazil | Jul 16, 1999 |
| Rodrigo Ruas (inactive) | | 0-1-0 | Brazil | Jun 22, 2002 |
| Robert Ruchala | Faker | 0-2-0 | Poland | Apr 4, 2026 |
| Gabe Ruediger (inactive) | Godzilla | 0-3-0 | United States | Feb 5, 2011 |
| Mauricio Ruffy | | 5-2-0 | Brazil | Sep 19, 2026 |
| Eddie Ruiz (inactive) | | 0-1-0 | United States | Jun 6, 2003 |
| Montserrat Conejo Ruiz | | 1-4-0 | Unknown | Nov 1, 2025 |
| Mike Russow (inactive) | | 4-2-0 | United States | Jan 26, 2013 |
| Bas Rutten (inactive) | El Guapo | 2-0-0 | Netherlands | May 7, 1999 |
| Nursulton Ruziboev | Black | 5-2-0 | Uzbekistan | Sep 5, 2026 |
| Damian Rzepecki | The Butcher | 0-1-0 | Poland | Jul 25, 2026 |