Hurling was a pillar of the education system in the school, pushed by two Tipperary men, Brother Cathal Duane (Kilruane) and Principal Barry O'Riordan (Nenagh).
On 11 March 2010, Hannon scored three points from play when Ardscoil Rís defeated Thurles CBS in the final of the Harty Cup.
On 18 October 2009, Hannon scored three points from right wing-forward when Adare defeated Na Piarsaigh by 1-17 to 0-03 in the final of the Limerick Senior Championship.
[8] On 17 April 2010, Hannon made his senior debut at right wing-forward for Limerick in a National League defeat of Antrim at Loughguile.
[15] On 19 August 2018, he scored two points from play and captained Limerick to their first All-Ireland title in 45 years after a 3-16 to 2-18 defeat of Galway in the final.
[19][20] On 31 March 2019, Hannon was selected at centre-back for Limerick's National League final meeting with Waterford at Croke Park.
[21] On 30 June 2019, Hannon won his first Munster Championship medal in six years after captaining Limerick to a 2-26 to 2-14 defeat of Tipperary in the final.
[citation needed] Hannon entered the history books in 2022 when he became the first hurling captain to lift the Liam MacCarthy Cup on four occasions.