He simultaneously came to prominence at juvenile and underage levels with the Cuala club, winning under-21 championship medals as a dual player.
Treacy subsequently joined the Cuala senior team and has enjoyed much success, culminating with the winning of an All-Ireland medal in 2017.
Treacy made his debut on the inter-county scene at the age of sixteen when he was selected for the Dublin minor teams in both codes.
He enjoyed two championship seasons with the minor teams, Leinster medals as both a Gaelic footballer and as a hurler.
Treacy made his senior debut during the 2009 league and has been a regular member of the starting fifteen since then.