The Offaly school trailed by six points early on in the contest.
A midlands school have been crowned All Ireland champions after the post-primary finals in Sligo on Saturday.
After needing extra time to emerge from the semi-finals, a late Senan Hanniffy point capped a determined fightback to win the Brother Edmund Ignatius Rice Cup for Gallen Community School at Markievicz Park.
The Offaly school trailed by 1-3 to no score at one point in the first half but managed to reel in Scoil Mhuire Buncrana to win the Senior D final.
The final score was 0-9 to 1-5.