*Club domestic league appearances and goals, correct as of 23:19, 28 April 2024 (UTC) ‡ National team caps and goals, correct as of 17:03, 11 June 2024 (UTC)
In January 2023, O'Mahony joined the academy of Brighton & Hove Albion for a reported fee of an initial £50,000, signing a three-year contract.[4] On 12 November 2023, he was named among the match day squad in the Premier League as Brighton played at home against Sheffield United.[5] On 10 April 2024, he signed a new contract with the club until June 2027.[6] On 13 April 2024, he made his senior debut for the club, coming off the bench in their 1–1 draw away to Burnley in the Premier League.[7]
On 28 April 2024, he made his first ever Premier League start vs Bournemouth, getting subbed off at half-time.
International career
He has been capped for Republic of Ireland at U-17, U-18 and U-19 levels, and was named the FAI’s U-17 Player of the Year in 2022.[8] In September 2022, he scored a hat trick for the Ireland U19 team against Gibraltar U19.[9] In December 2022 he was named the FAI U17 player of the year after scoring fourteen goals in sixteen appearances for Irish youth international teams.[10]