Zebo scored his first try for Ireland against Argentina on 24 November 2012, whilst playing at Fullback. Zebo was named in Ireland's training squad for the 2013 Six Nations Championship on 17 January 2013. He made his Six Nations debut on 2 February 2013, scoring a try as Ireland beat Wales 30–22 in the Millennium Stadium. Zebo hit the headlines when he used a back-heel flick to retain the ball in the lead-up to Cian Healy's try for Ireland against Wales. He started against England on 10 February 2013, but went off injured early in the first half. Zebo was ruled out for 10 weeks after suffering a broken foot during the match.