Inspired by county stars Cian Mackey and Ronan Flanagan, the Ballyjamesduff-based side consolidated their opening round thrashing (4-18 to 1-14) of Redhills with conviction and a swagger.
Castlerahan laid the foundations for their victory when racing into a 0-5 to 0-1 lead early on.
Gaels roared back in the second quarter with county star Martin Dunne nailed four points to cut the gap to two (0-7 to 0-5).
Shorn of the commanding presence of their centre-back Eamon Reilly, the Gaels’ soft centre was cruelly exposed in the 42nd minute when the winners notched the only goal of the game. Mackey found Oisin O’Connell with a superb pass and the finish was emphatic.
Another gem from Dunne (42) left just O’Connell’s major separating the two sides but, crucially, the 2011 champions failed to add a single score for a further 11 minutes.
Castlerahan comfortably consolidated their advantage with an inspirational point from centre-back Caolan McBreen (53) and a similar effort from Sean Brady.
Elsewhere in the SFC, Lacken Celtic catapulted a disappointing Drumalee side out of the competition on the back of a convincing 1-13 to 1-8 final scoreline.
Cavan SFC quarter-finals: Crosserlough v Cuchullains/Lavey , Ramor Utd v Castlerahan, Ballinagh v Killygarry/Lacken Celtic, Gowna/Mullahoran v Cavan Gaels/Kingscourt.