O'Brein represented Queensland in the 1997 State of Origin series. He played for the Newcastle Knights from the interchange bench in their 2001 NRL Grand Final victory over the Parramatta Eels. O'Brien played at from the interchange bench in Newcastle's loss.
A Queensland State of Origin representative forward, he played club football in Australia for the Sydney Roosters, South Queensland Crushers, Gold Coast Chargers and Newcastle Knights (with whom he won the 2001 NRL premiership), as well as English club Wakefield Trinity Wildcats. Having won the 2001 NRL Premiership, the Knights traveled to England to play the 2002 World Club Challenge against Super League champions, the Bradford Bulls.
