He played hurling at senior level for the Cork county team before becoming a professional Australian rules footballer.

This was considered surprising, as AFL recruiters in Ireland primarily targeted Gaelic footballers and Ó hAilpín had concentrated on hurling.

Ó hAilpín returned to Ireland in 2004 to play for the Irish team against Australia in the 2004 International Rules Series.

On 6 February 2009, Ó hAilpín was suspended indefinitely by the Carlton Football Club for his involvement in a violent altercation with teammate Cameron Cloke in an internal trial match.

[3] His actions were scrutinised by the AFL's match review panel on 9 February and he faced being forced into anger management counselling.

In Carlton's Round 11 clash with Brisbane at the Gabba, Ó hAilpín played his 50th AFL game, the third[citation needed] Irishman to achieve the milestone.

[8] During the AFL Trade Week at the end of 2010, Ó hAilpín was linked with a move to the Western Bulldogs after apparently being unhappy at being dropped from the Blues' side midway through the season and never getting back in.

[11] He played his first match for Greater Western Sydney in Round 6, 2012, against his former team Carlton, kicking two goals before rupturing his anterior cruciate ligament in the third quarter of the game.

[14] In December 2013, he was appointed by NSW/ACT, the governing body of Australian rules football in New South Wales, as the "Multicultural Program Coordinator" for Western Sydney.

[15] Since 2014, Ó hAilpín has played for Albury in the Ovens & Murray Football League, alongside brother Aisake;[16] he was the O&M's leading goalkicker in 2014, kicking 103 goals in the home-and-away season,[17] and was part of the club's premiership winning teams in 2014[18] and 2015.