 O'Brien became the first player to play international cricket after playing in the ICL when he played an Intercontinental Cup match against United Arab Emirates in March 2008; he went on to score 174 in Ireland's nine-wicket win.At the end of the 2008 season, O'Brien was named Northamptonshire's player of the year and was rewarded for his consistent performances with a three-year contract with the club.A representative of Northamptonshire CCC said "Niall, who has just returned from international duty, was in sensational form last season with the bat, scoring over 850 championship runs and piling on the runs in one-day competitions in a new pinch-hitter role".