 The well travelled O'Halloran joined Galway United in July 2007, signing from Derry City whom he had joined only a few months earlier in February 2007; this was after a year-long spell with Shelbourne where he won a League winners medal.The player had joined Shelbourne in December 2005 after spending eight seasons at Cork City.Having spent the beginning of his career at Crosshaven AFC, he moved to Leeds United and then to Hull City before moving to his home country.