Born in Brideswell, County Roscommon, O'Malley was introduced to Gaelic games during his schooling at Brideswell National School and the Marist College. At club level he first lined out as a minor dual player with Four Roads. In a distinguished career spanning over twenty years, O'Malley won seven championship medals as a hurler. As a Gaelic footballer he later moved to the St. Patrick's club before winning four championship medals with St. Brigid's.
