Tipperary star Lar Corbett banged in an early goal, but De La Salle responded with a Paudie Nevin goal.
Sarsfields led by 1-11 to 1-9 at half-time, and the Waterford men suffered a blow when John Keane was sent off.
Late points from Pa Bourke, Richie Ruth and Ger 'Redser' O'Grady sealed it for the Tipp champions.
St Brigid's of Roscommon won their third Connacht Club SFC title in a row, defeating Mayo's Ballaghderreen by 1-12 to 0-6 at Castlebar.
A closely fought first half saw Frankie Dolan, Senan Kilbride and Richard Blaine strike points for the defending champions, with Barry Regan and David Drake responding for the challengers, who trailed by 0-6 to 0-5 at half-time.
But St Brigid's dominated the second half, and Kilbride smashed home the only goal of the game to seal the provincial title.
Portlaoise of Laois set up a Leinster Club SFC final date with Dublin champions Ballymun Kickhams.
Brian Smith scored the vital goal as Portlaoise defeated Emmet Og Killoe of Longford by 1-11 to 2-5, while Ted Furman's goal helped Ballymun get the better of Sarsfields of Kildare by 1-8 to 0-5.