McFadden played with the Ireland A's in Denver, Colorado in the 2009 Churchill Cup. McFadden scored two tries in Ireland's victory over Georgia and kicked the conversion for one of those tries on 14 June 2009 at Infinity Park. In January 2011, McFadden was named in the starting team to play against Italy in the opening weekend of the 2011 Six Nations Championship, where he won his first cap. McFadden won his second cap starting against France in the same tournament, scoring his first try for Ireland in the process. On 08 June 2013, McFadden won his tenth cap starting against USA in the Irish tour to North America. Ireland won the game 15-12. On 15 June 2013, McFadden started against Canada scoring a hat-trick. Ireland won the game 40-14.