At club level he played with Kilruane MacDonaghs and was also a member of the Tipperary senior hurling team.
Hennessy was the youngest ever Kilruane player to line out in a North Tipperary SHC final when he did so as a 17-year-old in 1973.
He came on as a substitute for Enda Hogan at midfield when Kilruane MacDonaghs won the All-Ireland Club Championship title in 1986[3][4] Hennessy first appeared on the inter-county scene during a two-year tenure with the Tipperary minor hurling team.
[citation needed] Hennessy's performances at club level earned his inclusion on the senior team for the 1979 Munster SHC campaign.
[5] His son, also called Séamus Hennessy, was part of the Tipperary team that won the All-Ireland SHC title in 2010.