With the Central Coast Mariners he scored 8 goals from left back in 24 games and was subsequently named in FourFourTwo's A-League dream team.

Heffernan suffered a broken leg during the Mariners 4–5 loss to Sydney FC on 22 December 2007, due to a tackle by Ufuk Talay.

He planned to join Perth Glory for pre-season training in August after he had completed a short-term loan deal with Chinese Super League club Liaoning Whowin.

[2] On 30 August 2011, it was announced Perth Glory had agreed to release Heffernan after the player decided he would like to remain with Liaoning Whowin after the end of his loan deal.

[4] On 28 June 2013, it was announced that Heffernan had signed a one-year contract to play for Western Sydney Wanderers, following a short stint with Illawarra Premier League club Dapto Dandaloo Fury.

He got his first senior international cap on 28 January 2009 in an AFC Asian Cup qualifying match versus Indonesia at the Bung Karno Stadium in Jakarta.