Born in Knocktopher, County Kilkenny, Cummins first played competitive Gaelic games whilst at school in Belcamp College. He arrived on the inter-county scene at the age of seventeen when he first linked up with the Kilkenny minor team, before later joining the under-21 side. He made his senior debut in the 1966 Oireachtas Cup. Cummins went on to play a key part for Kilkenny for almost two decades, and won eight All-Ireland medals, nine Leinster medals and three National Hurling League medals. He was an All-Ireland runner-up on three occasions.