At club level, Cantwell progressed through the juvenile and underage ranks with the Shamrocks club before joining the club's adult teams as a dual player. He was part of the club's senior football team that beat Tubber in 2018 to win the Offaly SBFC title.[3]
Cantwell first appeared on the inter-county scene for Offaly during an unsuccessful one-year tenure with the under-20 team in 2020.[4] He was later drafted onto the senior team and made his debut in a National Hurling League defeat of Wicklow in 2021.[5] Cantwell won a Joe McDonagh Cup medal as an unused substitute in 2024 after a defeat of Laois in the final.[6]