| Yves Jabouin (inactive) | Tiger | 5-5-0 | United States | Aug 23, 2015 |
| Damon Jackson (inactive) | The Leech | 6-6-1 (1 NC) | United States | Nov 16, 2024 |
| Eugene Jackson (inactive) | The Wolf | 3-4-0 | United States | Jul 13, 2002 |
| Jeremy Jackson (inactive) | Scorpion | 0-2-0 | United States | Nov 11, 2006 |
| Kevin Jackson (inactive) | | 2-2-0 | Unknown | Mar 13, 1998 |
| Mike Jackson (inactive) | The Truth | 1-2-0 (1 NC) | United States | Oct 15, 2022 |
| Montel Jackson | Quik | 10-4-0 | United States | Sep 26, 2026 |
| Quinton Jackson (inactive) | Rampage | 8-5-0 | Unknown | Apr 25, 2015 |
| Dustin Jacoby | The Hanyak | 10-7-1 | United States | Jul 25, 2026 |
| Justin James (inactive) | | 0-1-0 | United States | Oct 14, 2006 |
| Virna Jandiroba | Carcara | 9-4-0 | Brazil | Apr 4, 2026 |
| Ryan Janes (inactive) | | 2-2-0 | Canada | Dec 1, 2017 |
| Milos Janicic | The Cobra | 0-1-0 | Montenegro | Aug 1, 2026 |
| Brock Jardine (inactive) | The Machine | 0-2-0 | United States | Feb 23, 2013 |
| Keith Jardine (inactive) | The Dean of Mean | 6-7-0 | United States | Jun 19, 2010 |
| Rony Jason (inactive) | | 4-4-0 (1 NC) | Brazil | Mar 11, 2017 |
| Jasmine Jasudavicius | | 9-3-0 | Canada | Apr 18, 2026 |
| Yazmin Jauregui | | 4-2-0 | Mexico | Sep 26, 2026 |
| Justin Jaynes (inactive) | The Guitar Hero | 1-4-0 | United States | Jun 26, 2021 |
| Joanna Jedrzejczyk (inactive) | | 10-5-0 | Poland | Jun 11, 2022 |
| Brandon Jenkins (inactive) | The Human Highlight Reel | 0-2-0 | United States | Apr 16, 2022 |
| Jack Jenkins | Phar | 4-3-0 | Australia | Aug 29, 2026 |
| Trent Jenkins (inactive) | | 0-1-0 | United States | Dec 16, 1995 |
| Steve Jennum (inactive) | | 2-1-0 | United States | Dec 16, 1995 |
| Ryan Jensen (inactive) | | 2-6-0 | United States | Apr 30, 2011 |
| Chan-Mi Jeon (inactive) | | 0-2-0 | South Korea | Sep 22, 2017 |
| Maciej Jewtuszko (inactive) | Irokez | 0-1-0 | Unknown | Feb 26, 2011 |
| Ronald Jhun (inactive) | The Machine Gun | 0-1-0 | United States | Aug 21, 2004 |
| Baergeng Jieleyisi (inactive) | | 0-1-0 | Unknown | Nov 23, 2024 |
| Ryan Jimmo (inactive) | The Big Deal | 3-4-0 | United States | May 30, 2015 |
| Li Jingliang | The Leech | 11-7-0 | China | Aug 17, 2024 |
| Xiong Jingnan | The Panda | 0-2-0 | China | Aug 29, 2026 |
| Sung Bin Jo (inactive) | Korean Falcon | 0-1-0 | Unknown | Jun 1, 2019 |
| Brett Johns (inactive) | The Pikey | 5-2-0 | United Kingdom | Jul 18, 2020 |
| Miles Johns | Chapo | 7-5-0 (1 NC) | United States | Aug 8, 2026 |
| Phil Johns (inactive) | | 0-1-0 | United States | Feb 23, 2001 |
| Anthony Johnson (inactive) | Rumble | 13-6-0 | United States | Apr 8, 2017 |
| Charles Johnson | InnerG | 9-7-0 | United States | Aug 15, 2026 |
| DaMarques Johnson (inactive) | Darkness | 4-6-0 | United States | Sep 29, 2012 |
| Dashon Johnson (inactive) | Flyboy | 0-2-0 | United States | Sep 13, 2014 |
| Demetrious Johnson (inactive) | Mighty Mouse | 15-2-1 | Unknown | Aug 4, 2018 |
| Donte Johnson | Lock Jaw | 3-0-0 | United States | Aug 15, 2026 |
| Jordan Johnson (inactive) | | 4-0-0 | United States | Sep 15, 2018 |
| Jose Johnson (inactive) | Zhakwarius | 1-3-0 | United States | Jan 11, 2025 |
| Kajan Johnson (inactive) | Ragin' | 4-3-0 | Canada | Sep 15, 2018 |
| Lavar Johnson (inactive) | Big | 2-2-0 | Unknown | Feb 23, 2013 |
| Michael Johnson | The Menace | 16-16-0 | United States | Mar 7, 2026 |
| Timothy Johnson (inactive) | | 4-3-0 | United States | Feb 3, 2018 |
| Ben Johnston | | 0-1-0 | Australia | May 2, 2026 |
| Brian Johnston (inactive) | | 2-4-0 | Unknown | Jul 27, 1997 |
| Liana Jojua (inactive) | She Wolf | 1-3-0 | Georgia | Nov 13, 2021 |
| Daniel Jolly (inactive) | The Werewolf of Texas | 0-2-0 | Unknown | Feb 4, 2017 |
| Jon Jones | Bones | 22-1-0 (1 NC) | United States | Nov 16, 2024 |
| Justin Jones (inactive) | Black Dynamite | 0-2-0 | Unknown | Apr 4, 2015 |
| Marcus Jones (inactive) | The Darkness | 0-1-0 | United States | Dec 5, 2009 |
| Mason Jones | The Dragon | 4-3-0 (1 NC) | United Kingdom | Aug 22, 2026 |
| Paul Jones (inactive) | | 1-1-0 | Unknown | Sep 24, 1999 |
| Trevin Jones (inactive) | 5 Star | 1-4-0 (1 NC) | United States | Mar 4, 2023 |
| Jocelyn Jones-Lybarger (inactive) | | 0-3-0 | United States | Jan 15, 2017 |
| Joe Jordan (inactive) | | 0-1-0 | United States | Jul 8, 2006 |
| Kevin Jordan (inactive) | The Shaman | 0-2-0 | United States | Nov 19, 2005 |
| Shawn Jordan (inactive) | The Savage | 6-4-0 | United States | Oct 3, 2015 |
| Ivan Jorge (inactive) | Batman | 2-2-0 | Brazil | Jul 18, 2015 |
| Scott Jorgensen (inactive) | Young Guns | 4-8-0 | United States | Nov 21, 2015 |
| Jeff Joslin (inactive) | The Inferno | 0-1-0 | Canada | Dec 13, 2006 |
| Krzysztof Jotko (inactive) | | 11-6-0 | Poland | Oct 1, 2022 |
| Alan Jouban (inactive) | Brahma | 8-5-0 | United States | Nov 21, 2020 |
| Charles Jourdain | Air | 9-8-1 | Canada | Sep 19, 2026 |
| Kevin Jousset (inactive) | Air | 2-2-0 | France | Feb 8, 2025 |
| Allen Frye Jr. | | 0-1-0 | United States | Dec 13, 2025 |
| Carlo Pedersoli Jr. (inactive) | Semento | 1-2-0 | Unknown | Feb 23, 2019 |
| Khalil Rountree Jr. | | 10-7-0 (1 NC) | United States | Oct 4, 2025 |
| Lance Gibson Jr. | Fearless | 1-1-0 | United States | Mar 28, 2026 |
| Levi Rodrigues Jr. | Baby Monster | 0-2-0 | Brazil | Aug 29, 2026 |
| Michael Aswell Jr. | The Texas Kid | 2-3-0 | United States | Sep 19, 2026 |
| Raul Rosas Jr. | El Nino Problema | 7-1-0 | United States | Sep 26, 2026 |
| Silvana Gomez Juarez (inactive) | La Malvada | 1-3-0 | Argentina | Nov 12, 2022 |
| Anshul Jubli | King of Lions | 1-2-0 | India | Feb 8, 2025 |
| Carli Judice | Crispy | 4-1-0 | United States | Aug 22, 2026 |
| Steve Judson (inactive) | | 0-2-0 | Unknown | Mar 10, 2000 |
| Luke Jumeau (inactive) | The Jedi | 2-2-0 | Australia | Oct 5, 2019 |
| Chan Sung Jung | The Korean Zombie | 7-5-0 | South Korea | Aug 26, 2023 |
| Da Woon Jung (inactive) | Sseda | 4-4-1 | South Korea | Sep 28, 2024 |
| Antonio Carlos Junior (inactive) | Cara de Sapato | 7-5-0 (1 NC) | Brazil | Jan 23, 2021 |
| Marcio Alexandre Junior | Lyoto | 0-3-0 | Brazil | Dec 12, 2015 |
| Scott Junk (inactive) | | 0-1-0 | United States | Sep 22, 2007 |
| Myles Jury (inactive) | Fury | 8-4-0 | United States | Feb 17, 2019 |
| Cristiane Justino (inactive) | Cyborg | 6-1-0 | Unknown | Jul 27, 2019 |