A Mackay Brothers junior, O'Hanlon was signed by Parramatta after being selected for Queensland U/18's & Australian schoolboys.

O'Hanlon made his NRL debut in round 17, 2011 against the Brisbane Broncos, coming off the bench to play centre for the injured Jacob Loko.

O'Hanlon played nine games in his debut season for Parramatta as the club narrowly avoided the wooden spoon.

Parramatta defeated the Gold Coast in the final round of the regular season at Cbus Super Stadium to avoid the dreaded award.

In the first week of the 2014 NRL finals series, O'Hanlon suffered a compound left leg fracture.