At club level he played with Midleton, Blackrock, St Finbarr's and Castlemartyr and was also a member of the Cork senior hurling team.
Born in Ballinacurra, County Cork, O'Sullivan first played hurling at juvenile and underage levels with the St Enda's club.
He enjoyed his first success in 1938 when the club secured the Cork MHC title after a defeat of Seán Clárach's in the final.
By that stage O'Sullivan had also joined the Midleton senior team and was full-forward when they suffered a defeat by Glen Rovers in the 1938 final.
O'Sullivan's performances at juvenile level with St Enda's resulted in him being drafted onto the Cork minor hurling team in 1938.
[8] O'Sullivan was at full-forward for the 1939 All-Ireland final defeat by Kilkenny, however, he ended the championship Cork's top scorer with 7-01.