History of Sean O'Malley (fighter) in Timeline

Sean O'Malley is an American professional mixed martial artist who competes in the Bantamweight division of the Ultimate Fighting Championship (UFC). He is a former UFC Bantamweight Champion and, as of March 2026, is ranked #2 in the UFC bantamweight rankings. O'Malley is known for his striking abilities and unique personality.

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Full Timeline Career & Achievements

October 24, 1994: Sean O'Malley's Birth

Sean Daniel O'Malley was born on October 24, 1994. He is an American professional mixed martial artist.

December 1, 2017: UFC Debut vs Terrion Ware

On December 1, 2017, Sean O'Malley made his promotional debut against Terrion Ware at The Ultimate Fighter 26 Finale, winning by unanimous decision.

March 3, 2018: Fight against Andre Soukhamthath

On March 3, 2018, Sean O'Malley faced Andre Soukhamthath at UFC 222, winning by unanimous decision despite a foot injury during the fight. Both fighters earned a Fight of the Night bonus.

October 6, 2018: Pulled from UFC 229

On October 6, 2018, Sean O'Malley was expected to fight José Alberto Quiñónez at UFC 229 but had to withdraw from the fight on September 30 due to a potential Anti-Doping Policy violation.

March 2019: Return Eligibility

In March 2019, Sean O'Malley became eligible to return to fighting after serving a suspension for an Anti-Doping Policy violation. He was suspended for six months by the NSAC after testing positive for ostarine.

June 21, 2019: Withdrawal announcement from UFC 239

On June 21, 2019, Sean O'Malley announced his withdrawal from the bout with Marlon Vera scheduled for July 6, 2019 at UFC 239, due to a failed test for ostarine.

July 6, 2019: Withdrawal from UFC 239

On July 6, 2019, Sean O'Malley was scheduled to face Marlon Vera at UFC 239. However, he announced his withdrawal from the bout on June 21, 2019, due to a failed test for ostarine. He was suspended for 6 months by USADA.

December 12, 2019: Competed at Quintet: Ultra

On December 12, 2019, Sean O'Malley competed at Quintet: Ultra as a member of Team UFC. He submitted Takanori Gomi but was later submitted by Héctor Lombard. Team UFC ended up winning the tournament.

March 7, 2020: Fight against José Alberto Quiñónez

On March 7, 2020, Sean O'Malley fought José Alberto Quiñónez at UFC 248 and won via TKO in the first round, earning his first Performance of the Night award.

June 6, 2020: Fight against Eddie Wineland

On June 6, 2020, Sean O'Malley faced Eddie Wineland at UFC 250 and won by a one-punch knockout in the first round, earning him a Performance of the Night award.

August 15, 2020: Fight against Marlon Vera

On August 15, 2020, Sean O'Malley faced Marlon Vera at UFC 252 and lost via TKO in round one, marking the first defeat of his career. He was later diagnosed with drop foot due to a leg kick from Vera.

September 20, 2020: Grappling Industries Phoenix

On September 20, 2020, Sean O'Malley entered the 155lbs Advanced No-gi division of Grappling Industries Phoenix, placing third in a seven-man division, losing only to Robert Degle.

December 20, 2020: SUG Grappling Match Challenge

On December 20, 2020, Chael Sonnen put out an open challenge on behalf of Sean O'Malley for his promotion's event. James Gallagher challenged O'Malley to a grappling match at the SUG event, but O'Malley declined.

2020: Birth of Daughter

In 2020, Sean O'Malley and his wife had a daughter.

March 27, 2021: Fight against Thomas Almeida

On March 27, 2021, Sean O'Malley faced Thomas Almeida at UFC 260. He won the fight via knockout in the third round, earning him the Performance of the Night award.

July 10, 2021: Fight against Kris Moutinho

On July 10, 2021, Sean O'Malley was originally scheduled to face Louis Smolka at UFC 264, but faced Kris Moutinho after Smolka pulled out. O'Malley won the bout via TKO in round three, earning him the Fight of the Night award.

December 11, 2021: Fight against Raulian Paiva

On December 11, 2021, Sean O'Malley faced Raulian Paiva at UFC 269, winning the fight via TKO in round one. This win earned O'Malley his fourth Performance of the Night bonus award.

July 2, 2022: Fight against Pedro Munhoz

On July 2, 2022, Sean O'Malley faced Pedro Munhoz at UFC 276. The fight was declared a no contest after O'Malley accidentally poked Munhoz in the eye, rendering him unable to continue early in the second round.

October 22, 2022: Fight against Petr Yan

On October 22, 2022, Sean O'Malley faced former UFC Bantamweight champion Petr Yan at UFC 280. He won the bout via split decision in a highly controversial result, receiving the Fight of the Night bonus. The editors of Sherdog website gave this fight "2022 Robbery of the Year Award".

August 19, 2023: Won UFC Bantamweight Championship

On August 19, 2023, Sean O'Malley faced Aljamain Sterling for the UFC Bantamweight Championship at UFC 292. He won the title by second-round technical knockout, earning him another Performance of the Night bonus.

March 9, 2024: Title Defense against Marlon Vera

On March 9, 2024, Sean O'Malley faced Marlon Vera in a rematch at UFC 299 for his first title defense. He defended his title via unanimous decision, earning him his sixth Performance of the Night bonus award.

September 14, 2024: Title Loss against Merab Dvalishvili

On September 14, 2024, Sean O'Malley faced Merab Dvalishvili in a rematch for his second title defense at UFC 306, losing the fight by unanimous decision. He later revealed he suffered from a torn labrum.

May 2025: Birth of Son

In May 2025, Sean O'Malley and his wife had a son.

June 7, 2025: Fight against Merab Dvalishvili

On June 7, 2025, Sean O'Malley faced Merab Dvalishvili in a rematch for the championship at UFC 316. He lost the fight via a north-south choke submission at the end of the third round.

January 24, 2026: Fight against Song Yadong

On January 24, 2026, Sean O'Malley faced Song Yadong at UFC 324, winning the bout by unanimous decision. Media outlets were split in their scoring of the bout.