O’Brien was part of the Dragons U18s set-up and went on to earn 7 caps for Wales U20s. He was Dragons’ top points scorer in 2016-17 and had previously played for Principality Premiership side Cross Keys, making his regional debut on 12th September 2014, aged just 19 years old.
O'Brien was also part of the Dragons 7s team that were crowned champions of the Premiership Sevens in 2015 and represented Wales in the Gold Coast Commonwealth Games.