Casey first came to prominence on the inter-county scene at the age of eighteen when he was a key member of the Mayo junior team. He won an All-Ireland medal in 1951 before being promoted to the senior grade the following year. Casey made his debut during the 1951-52 league. Over the course of the next thirteen seasons he became a regular member of the starting fifteen and won one Connacht medal and one National Football League medal as a member of the extended panel. He played his last game for Mayo in July 1964.
