Steve O'Brien joined Canterbury in 1983 as a centre.
In 1984, Steve became a regular member of the reserve grade team as a centre before receiving the opportunity to play first grade against South Sydney when Max Mannix was relegated.
Steve played in the Premiership winning team against Parramatta.
In 1985, Steve started the season in first grade but was relegated mid-season when Chris Mortimer returned from injury. He played in the Reserve grade Semi-Final against Canberra.
In 1986, Steve returned to first grade and played in the Grand Final against Parramatta.