O'Sullivan first played hurling at juvenile and underage levels with Ballygunner, winning a Waterford MHC medal in 1992.
He was also a member of the extended panel of the club's senior team that also claimed the Waterford SHC title that year.
[6] O'Sullivan later progressed to under-21 level and made a number of appearances for the senior team in challenge games.
[8] O'Sullivan's time in charge also saw Ballygunner beat Ballyhale Shamrocks in the 2022 All-Ireland club final.
[9] His brothers, Billy and Shane O'Sullivan, as well as his nephews, Philip, Kevin ,Pauric Mahony and Patrick Fitzgerald , also played with Ballygunner and the Waterford senior team.