Pierce O'Leary (born 28 February 2000) is an Irish professional boxer who has held the IBO super-lightweight title since March 2026. He is also a former European and WBC International champion in the same weight division.
A nine-time Irish amateur champion, O'Leary turned professional in 2019, signing a promotional contract with MTK Global. He made his pro-debut on 11 October that year, defeating Oscar Amador on points over four rounds at Ulster Hall in Belfast.
Unbeaten in his first 10 professional fights and now signed to Frank Warren's Queensbury Promotions, O'Leary claimed the vacant WBC International super-lightweight title thanks to a unanimous decision win over Emmanuel Mungandjela at the O2 Arena in London on 26 November 2022.
He made the first defense of his championship at the SSE Arena in Belfast on 27 May 2023, stopping Alin Florin Ciorceri in the first round.
On 23 September 2023, he retained his title with a unanimous decision victory over Kane Gardner at Wembley Arena in London.
Two more successful defenses followed as O'Leary stopped Hovhannes Martirosyan in the ninth round at Resorts World Arena in Birmingham on 16 March 2024, and then prevailed via unanimous decision against Darragh Foley back at the SSE Arena in Belfast on 28 June 2024.
In his next outing, he stopped Jose Edgardo Perdomo in the third of their scheduled eight-round non-title contest at Wembley Arena in London on 7 December 2024.
O'Leary defended his championship for the fifth time against Liam Dillon at Portman Road in Ipswich on 7 June 2025, with the vacant European super-lightweight title also on the line. He won via unanimous decision.
He was scheduled to face Mark Chamberlain for the vacant IBO super-lightweight title at 3Arena in Dublin on 14 March 2026. However, Chamberlain withdrew two weeks before the fight was due to take place due to illness and was replaced by Maxi Hughes. O'Leary won when Hughes retired on his stool at the end of the fifth round.