His league and championship career with the Offaly senior team spanned eighteen seasons from 1976 to 1992.
[citation needed] Mooney made his senior debut for Offaly during the 1976 championship becoming the youngest player ever to play for the county.
He also played against Kerry for the San Francisco Allstars in 1981 in Balboa Stadium.
He was a player-manager for Warwickshire GAA when they won the British Championship in the early nineties.
[citation needed] Bono famously wore Johnny’s Offaly jersey during a concert in Germany back In 1983.