The team beat De La Salle, Waterford by the slimmest of margins in the Umbro FAI Schools Minor Boys cup final.
The only difference between the sides was a 43 minute goal from Kieran McPherson at the Oscar Traynor Centre in Cooklock, Dublin.
McPherson hit the net following an excellent turn in the box and coolly slotted into the bottom corner past De Le Salle goalkeeper Stephen Doheny, finishing with real aplomb.
This now means the U-15 trophy can be added the U-17 triumph won days earlier against the same opponents, Munster champions De La Salle.
With just one goal between the sides, Waterford pushed and practically camped in the Donegal side’s box for the last 20 minutes.
However Ollie Horgan’s side battened down the hatches and followed in the footsteps of their more senior boys.
St. Eunan’s College, Letterkenny: Rory Carr, Nathan McElwaine, Darragh Harper, Liam Blaney, Darragh McWalters, Oisin Hassett, Paul O’Brien, Ciaran Maloney, Kieran Mc Pherson, Patrick Diver, Caolan McDaid.