Usually lining out as a goalkeeper, he was a member of the Galway team that won the 1923 All-Ireland Championship.
He is regarded as one of the club's greatest-ever players and was included on a special Team of the Millennium.
Mahony was a runner-up in four subsequent All-Ireland finals and retired from inter-county hurling in 1929.
As one of the top goalkeepers of his era, Mahony was included on the Ireland team at the Tailteann Games in 1924, for which he was awarded a gold medal.
[citation needed] Mahony was also a member of the Old IRA and was interned at Ballykinlar and other camps during the War of Independence.