| Danny Abbadi (inactive) | The Assassin | 0-2-0 | United States | Sep 23, 2006 |
| David Abbott (inactive) | Tank | 8-10-0 | Unknown | Nov 21, 2003 |
| Hamdy Abdelwahab (inactive) | The Hammer | 2-1-0 (1 NC) | Egypt | Oct 25, 2025 |
| Mansur Abdul-Malik | | 3-2-1 | United States | Aug 15, 2026 |
| Tahir Abdullayev | Tank | 1-0-0 | Azerbaijan | Jun 27, 2026 |
| Shamil Abdurakhimov (inactive) | Abrek | 5-6-0 | Russia | Jan 21, 2023 |
| Daichi Abe (inactive) | | 1-2-0 | Japan | Jun 23, 2018 |
| Papy Abedi (inactive) | Makambo | 1-3-0 | Unknown | Aug 28, 2013 |
| Klidson Abreu (inactive) | White Bear | 1-2-0 (1 NC) | Brazil | May 30, 2020 |
| Ricardo Abreu (inactive) | Demente | 1-1-0 | Brazil | Jun 6, 2015 |
| Waldo Cortes Acosta | Salsa Boy | 10-4-0 | Dominican Republic | Sep 12, 2026 |
| Juan Adams (inactive) | The Kraken | 1-3-0 | United States | Feb 8, 2020 |
| Scott Adams (inactive) | | 1-0-0 | Unknown | Mar 10, 2000 |
| Zarrukh Adashev (inactive) | The Lion | 1-3-0 | Uzbekistan | Jun 4, 2022 |
| Israel Adesanya | The Last Stylebender | 13-6-0 | Nigeria | Mar 28, 2026 |
| Sam Adkins (inactive) | The Experience | 2-2-0 | United States | Sep 20, 1996 |
| Nick Agallar (inactive) | | 0-1-0 | United States | Nov 21, 2003 |
| Mariya Agapova (inactive) | Money Mashka | 2-4-0 | Kazakhstan | Jul 13, 2024 |
| Marcelo Aguiar (inactive) | | 0-1-0 | Brazil | Jun 9, 2000 |
| Jessica Aguilar (inactive) | Jag | 1-4-0 | United States | Mar 30, 2019 |
| Jesus Aguilar (inactive) | | 4-3-0 | Mexico | Mar 7, 2026 |
| Kevin Aguilar (inactive) | Angel of Death | 2-4-0 | United States | May 15, 2021 |
| Christian Aguilera (inactive) | The Beast | 1-2-0 | United States | May 8, 2021 |
| Nick Aguirre (inactive) | Slick | 0-2-0 | United States | Nov 18, 2023 |
| Omari Akhmedov (inactive) | Wolverine | 9-5-1 | Russia | Jul 10, 2021 |
| Yoshihiro Akiyama (inactive) | | 2-5-0 | Japan | Nov 28, 2015 |
| Rostem Akman (inactive) | | 0-2-0 | Sweden | Oct 5, 2019 |
| Ilimbek Akylbek | | 1-0-0 | Kyrgyzstan | Sep 26, 2026 |
| Razak Al-Hassan (inactive) | | 0-2-0 | United States | Oct 24, 2009 |
| Abdul-Kareem Al-Selwady | Pride of Palestine | 1-1-0 | United States | Mar 21, 2026 |
| Mostapha Al-Turk (inactive) | | 0-3-0 | Lebanon | Apr 10, 2010 |
| Ali AlQaisi (inactive) | The Royal Fighter | 0-2-0 | Jordan | Oct 10, 2020 |
| Alatengheili | The Mongolian Knight | 6-3-1 | Unknown | Sep 26, 2026 |
| Amir Albazi | The Prince | 5-2-0 | Iraq | Feb 7, 2026 |
| John Albert (inactive) | Prince | 1-4-0 | United States | Jul 27, 2013 |
| Junior Albini (inactive) | Baby | 1-4-0 | Brazil | Jun 29, 2019 |
| Wes Albritton (inactive) | | 0-1-0 | United States | May 30, 1997 |
| Aleksandra Albu (inactive) | Stitch | 2-2-0 | Moldova | Oct 26, 2019 |
| Ildemar Alcantara (inactive) | Marajo | 4-3-0 | Unknown | Jul 15, 2015 |
| Iuri Alcantara (inactive) | Marajo | 10-7-0 (1 NC) | Brazil | Aug 25, 2018 |
| Alfonso Alcarez (inactive) | | 0-0-1 | United States | Sep 24, 1999 |
| Gilbert Aldana (inactive) | El Peligro | 0-2-0 | United States | Jul 8, 2006 |
| Hector Aldana (inactive) | | 0-3-0 | Mexico | Oct 12, 2019 |
| Irene Aldana (inactive) | | 8-6-0 | Mexico | Sep 14, 2024 |
| Jose Aldo (inactive) | | 14-9-0 | Brazil | May 10, 2025 |
| JJ Aldrich | | 11-7-0 | United States | Sep 12, 2026 |
| Irina Alekseeva (inactive) | Russian Ronda | 1-3-0 | Kazakhstan | Oct 11, 2025 |
| Talita Alencar | Problem Child | 4-1-0 | Brazil | Apr 25, 2026 |
| Jim Alers (inactive) | The Beast | 1-2-0 (1 NC) | United States | Jul 23, 2016 |
| John Alessio (inactive) | The Natural | 0-5-0 | United States | Jul 7, 2012 |
| Houston Alexander (inactive) | The Assassin | 2-4-0 | United States | Dec 5, 2009 |
| Lucas Alexander (inactive) | The Lion | 1-3-0 | Brazil | Feb 1, 2025 |
| Bill Algeo (inactive) | Senor Perfecto | 5-5-0 | United States | Jul 20, 2024 |
| Royce Alger (inactive) | | 0-2-0 | United States | Jul 16, 1999 |
| Abdul Razak Alhassan (inactive) | | 6-7-0 (1 NC) | Ghana | Jan 11, 2025 |
| Nurullo Aliev | Tajik Eagle | 4-0-0 | Tajikistan | Jul 25, 2026 |
| Sultan Aliev (inactive) | | 2-2-0 | Russia | Apr 20, 2019 |
| Ikram Aliskerov | | 5-1-0 | Russia | Jun 27, 2026 |
| Michael Aljarouj | The Soldier | 0-1-0 | Syria | Sep 5, 2026 |
| John Allan (inactive) | | 0-2-0 (1 NC) | Brazil | Nov 6, 2021 |
| Arnold Allen | Almighty | 12-3-0 | United Kingdom | May 16, 2026 |
| Brendan Allen | All In | 15-4-0 | United States | Jun 6, 2026 |
| Ben Alloway (inactive) | Blanco | 1-2-0 | Australia | Aug 28, 2013 |
| Asu Almabayev | Zulfikar | 7-1-0 | Kazakhstan | Jun 27, 2026 |
| Bekzat Almakhan (inactive) | The Turan Warrior | 1-3-0 | Kazakhstan | Jun 27, 2026 |
| Cesar Almeida | Cesinha | 3-3-0 | Brazil | Jul 11, 2026 |
| Ericka Almeida (inactive) | | 0-2-0 | United States | Oct 24, 2015 |
| Jailton Almeida (inactive) | Malhadinho | 8-3-0 | Brazil | Feb 7, 2026 |
| Lucas Almeida (inactive) | | 2-4-0 | Brazil | Oct 11, 2025 |
| Ricardo Almeida (inactive) | Big Dog | 6-5-0 | United States | Mar 19, 2011 |
| Thomas Almeida (inactive) | Thominhas | 5-5-0 | Brazil | Mar 27, 2021 |
| Sarah Alpar (inactive) | Too Sweet | 0-2-0 | United States | Sep 18, 2021 |
| Victor Altamirano (inactive) | El Magnifico | 2-4-0 | Mexico | Sep 28, 2024 |
| Eddie Alvarez (inactive) | | 4-3-0 (1 NC) | United States | Jul 28, 2018 |
| Joel Alvarez | El Fenomeno | 8-4-0 | Spain | Aug 15, 2026 |
| Sean Alvarez (inactive) | | 0-1-0 | United States | Apr 25, 2003 |
| Amilcar Alves (inactive) | | 0-2-0 | Brazil | Jan 22, 2011 |
| Rafael Alves (inactive) | The Turn | 1-3-0 | Brazil | Feb 25, 2023 |
| Thiago Alves (inactive) | Pitbull | 15-12-0 | Brazil | Dec 7, 2019 |
| Warlley Alves (inactive) | | 8-8-0 | Brazil | May 18, 2024 |
| Sam Alvey (inactive) | Smile'N | 10-13-1 | United States | Aug 6, 2022 |
| Adlan Amagov (inactive) | Borz | 2-0-0 | Russia | Oct 19, 2013 |
| Melissa Amaya | Mamba | 0-1-0 | United States | Sep 26, 2026 |
| Alen Amedovski (inactive) | | 0-4-0 | North Macedonia | Sep 17, 2022 |
| Hyder Amil | The Hurricane | 3-3-0 | Philippines | Jun 20, 2026 |
| Makwan Amirkhani (inactive) | Mr. Finland | 7-7-0 | Iraq | Mar 18, 2023 |
| Jaqueline Amorim | | 5-2-0 | Brazil | May 30, 2026 |
| Yaroslav Amosov | | 2-0-0 | Ukraine | May 9, 2026 |
| Eryk Anders (inactive) | Ya Boi | 10-9-0 (1 NC) | United States | Mar 14, 2026 |
| Matt Andersen (inactive) | | 0-1-0 | United States | May 17, 1996 |
| Andy Anderson (inactive) | The Hammer | 0-1-0 | United States | Apr 7, 1995 |
| Corey Anderson (inactive) | Overtime | 10-5-0 | United States | Feb 15, 2020 |
| Damien Anderson | Demon Hands | 0-1-0 | United States | Jul 18, 2026 |
| Lowell Anderson (inactive) | | 0-1-0 | Unknown | Sep 24, 1999 |
| Megan Anderson (inactive) | | 3-3-0 | Australia | Mar 6, 2021 |
| Alex Andrade (inactive) | El Toro | 0-1-0 | United States | Jun 9, 2000 |
| Douglas Silva de Andrade | D Silva | 7-7-0 | Brazil | Feb 28, 2026 |
| Jessica Andrade | Bate Estaca | 17-13-0 | Brazil | Aug 16, 2025 |
| Viscardi Andrade (inactive) | | 3-1-0 | Brazil | Mar 19, 2016 |
| Jermaine Andre (inactive) | | 0-1-0 | Unknown | Mar 10, 2000 |
| Dylan Andrews (inactive) | The Villain | 2-3-0 | Australia | May 9, 2015 |
| Pavel Andrusca | | 1-0-0 | Moldova | Sep 5, 2026 |
| Reese Andy (inactive) | Riptide | 0-2-0 | United States | Dec 27, 2008 |
| Collin Anglin (inactive) | | 0-2-0 | United States | Nov 13, 2021 |
| Chad Anheliger | The Monster | 2-3-0 | Canada | Nov 2, 2024 |
| Yoji Anjo (inactive) | Mr. 200% | 0-3-0 | United States | Dec 16, 2000 |
| Rafael Dos Anjos | | 21-16-0 | Brazil | Oct 3, 2026 |
| Magomed Ankalaev | | 13-2-1 (1 NC) | Russia | Jul 25, 2026 |
| Gadzhimurad Antigulov (inactive) | | 2-4-0 | Russia | Oct 17, 2020 |
| Azunna Anyanwu (inactive) | Zulu | 0-1-0 | Unknown | Sep 16, 2017 |
| Shinsho Anzai (inactive) | Animal | 2-2-0 | Japan | Jun 23, 2018 |
| Aoriqileng (inactive) | The Mongolian Murderer | 4-6-0 (1 NC) | China | Aug 29, 2026 |
| Romie Aram (inactive) | | 0-1-0 | United States | Apr 25, 2003 |
| Felipe Arantes (inactive) | Sertanejo | 5-6-1 | Brazil | Jun 23, 2018 |
| Igor Araujo (inactive) | | 2-2-0 | United States | Jul 15, 2015 |
| Viviane Araujo (inactive) | Vivi | 7-6-0 | Brazil | Jun 28, 2025 |
| Julio Arce (inactive) | | 6-4-0 | United States | Mar 30, 2024 |
| Alice Ardelean | | 3-2-0 | Romania | May 16, 2026 |
| Dan Argueta (inactive) | The Determined | 1-3-0 (2 NC) | United States | Oct 12, 2024 |
| Andrei Arlovski (inactive) | The Pitbull | 23-18-0 (1 NC) | United States | Jun 29, 2024 |
| Lucas Armand | Do or Die | 0-1-0 | United States | Oct 3, 2026 |
| Garrett Armfield | | 2-3-0 | United States | Nov 2, 2024 |
| Austin Arnett (inactive) | | 1-3-0 | United States | Feb 9, 2019 |
| Akbarh Arreola (inactive) | El Caballero | 1-3-0 | Mexico | Nov 14, 2015 |
| Antonio Arroyo (inactive) | | 0-3-0 | Brazil | Sep 18, 2021 |
| Matt Arroyo (inactive) | No Regard | 1-2-0 | United States | Jan 31, 2009 |
| Mike van Arsdale (inactive) | | 2-2-0 | United States | Feb 4, 2006 |
| Cesar Arzamendia (inactive) | Goku | 0-2-0 | Paraguay | Jul 30, 2016 |
| Kai Asakura | | 2-2-0 | Japan | Aug 29, 2026 |
| Yanal Ashmouz (inactive) | Red Fox | 2-2-0 | Israel | Jun 7, 2025 |
| Askar Askarov (inactive) | Bullet | 3-1-1 | Russia | Mar 26, 2022 |
| Cyril Asker (inactive) | Silverback | 2-3-0 | France | Feb 10, 2018 |
| Khusein Askhabov (inactive) | Nohcho | 0-1-0 | Russia | Feb 18, 2023 |
| Scott Askham (inactive) | | 2-4-0 | United Kingdom | Mar 18, 2017 |
| Ben Askren (inactive) | Funky | 1-2-0 | United States | Oct 26, 2019 |
| Ibo Aslan | The Last Ottoman | 2-3-0 | Türkiye | Dec 6, 2025 |
| Tom Aspinall | | 8-1-0 (1 NC) | United Kingdom | Oct 25, 2025 |
| Steven Asplund | Concrete | 2-1-0 | United States | Aug 8, 2026 |
| Junior Assuncao (inactive) | | 2-3-0 | Brazil | Dec 30, 2011 |
| Raphael Assuncao (inactive) | | 12-7-0 | Brazil | Mar 11, 2023 |
| Rich Attonito (inactive) | The Raging Bull | 3-2-0 | United States | Dec 10, 2011 |
| Olivier Aubin-Mercier (inactive) | The Canadian Gangster | 7-5-0 | Canada | Jul 27, 2019 |
| Pat Audinwood (inactive) | Awesomely Awesome | 0-2-0 | United States | Dec 11, 2010 |
| Marcus Aurelio (inactive) | Maximus | 2-4-0 | Brazil | Aug 29, 2009 |
| Chris Avila (inactive) | | 0-2-0 | United States | Nov 5, 2016 |
| Julia Avila (inactive) | Raging Panda | 3-3-0 | United States | Feb 15, 2025 |
| Jessin Ayari (inactive) | | 1-3-0 | Germany | Oct 3, 2020 |
| Abu Azaitar (inactive) | Captain Morocco | 1-2-0 | Morocco | Oct 21, 2023 |
| Ottman Azaitar | Bulldozer | 2-3-0 | Morocco | Dec 14, 2024 |
| Hunter Azure (inactive) | | 2-2-0 | United States | Apr 10, 2021 |