of Thurles CBS in a final replay. University College Cork On 3 March 2012, Mahony was selected at midfield when UCC qualified to play the Cork Institute of Technology in the Fitzgibbon Cup final. He ended the game with a winners' medal after the 2–15 to 2–14 victory. Ballygunner Minor and under-21 Mahony joined the Ballygunner club at a young age and came to prominence during the club's underage boom. On 12 November 2006, he was just 15-years-old when he lined out at right wing-back when Ballygunner faced Cappoquin in the Minor A Championship final. Mahony ended the game with his first winners' medal in that grade following the 2–12 to 2–05 victory. On 30 September 2007, Mahony was selected at centre-back when Ballygunner qualified for a second successive Minor A Championship final. He claimed a second winners' medal after the 3–24 to 2–09 defeat of Dungarvan. Mahony was in his fourth and final year with the Ballygunner minor team when he was appointed captain of the team. On 8 November 2009, he lined out in a third Minor A Championship final in four seasons when he was selected at right wing-back against a Dunhill-Fenor amalgamation. Mahony claimed a third winners' medal and had the honour of lifting the cup as captain after the 2–17 to 0–10 victory. Mahony was still eligible for the minor grade when he was selected for the Ballygunner under-21 team. On 6 December 2009, he lined out at centre-back in the Under-21 A Championship final against Dungarvan. Mahony claimed his first winners' medal in the grade after a 1–07 to 1–06 victory. On 29 August 2010, Mahony again lined out at centre-back in a second successive Under-21 A Championship final. He ended the game by collecting a second successive winners' medal after a second successive 2–18 to 1–11 defeat of Dungarvan. Mahony lined out in a third successive Under-21 A Championship final on 20 November 2011. Playing in his customary position of centre-back, he ended the game with a third successive under-21 championship winners' medal after the 4–23 to 0–10 defeat of Cappoquin. On 17 November 2012, Mahony lined out in a fourth successive Under-21 A Championship final. In what was his last game for the under-21 team, he collected a fourth and final winners' medal after the 1–13 to 0–15 defeat of St. Carthage's. Senior Mahony was still eligible for the minor grade when