A key member of the Bulldogs during the 'entertainers' era, one of his finest moments was kicking six conversions from six attempts in Canterbury's 1980 Grand Final victory.
Canterbury-Bankstown Bulldogs "GB (Brentnall) kicked the ball, I ran after it and it pretty much fell into my arms.
In 1974, he was spotted by Canterbury-Bankstown CEO Peter Moore when he was playing for Christian Brothers Lewisham in the Commonwealth Bank Cup Schoolboys rugby league competition.
He made his first grade début for the Berries during the 1976 NSWRFL season in Canterbury's 23–20 win against the Newtown Jets at Belmore Sports Ground.
Steve played in Canterbury's Heartbreaking 22–15 loss in the 1978 NSWRFL season's Qualifying Final against the Parramatta Eels.
He played in Canterbury's 17 – 13 1979 NSWRFL season's Grand Final loss to the St. George Dragons where he scored one try and booted two goals.
He played in Canterbury's 18 – 4 1980 Grand Final victory over the Eastern Suburbs Roosters where he scored one of the greatest ever 1st grade Australian rugby league Grand Final tries in history in which he chased, caught and grounded a classic try off a Greg Brentnall bomb.
In the 1983 Qualifying Final he kicked the two winning goals for the Saints to beat the Balmain Tigers 17–14.
After 9 Rounds of the 1986 NSWRL season Gearin lost patience as he was fed up playing in Reserve Grade and he realised that under Warren Ryan and competing for a starting spot on the wing with young, talented and hungry players like Steve O'Brien, Matthew Callinan and Sandy Campbell, he was not part of the club's future plans in first grade and as a result, the next week he requested a release from the club which was accepted by club CEO Peter Moore and Gearin decided to join the Manly Warringah Sea Eagles in search for any opportunity to revive his First Grade career and for geographical reasons as he lives and works in the Manly area.
At the end of the 1986 season he decided to Retire due to a mixture of falling out of love and interest with the game and wanting to focus on his School-teaching career and his family.