The County Down school led 0-9 to 0-4 at half-time and extended their lead to six points by the conclusion.
Rian O'Neill top-scored for the winners with 0-7, while Cian McConville contributed 0-2. Tiernan Kelly recorded three points for St Ronan's.
St Mary's Magherafelt and St Paul's Bessbrook must replay their semi-final.
The schools played out a 1-12 to 1-12 draw in the opening semi-final at the Dub on Wednesday and are set to meet next week at a venue still to be finalised.
St Colman's Newry progressed to the MacRory Cup final by beating St Ronan's Lurgan 0-14 to 0-8 in Thursday night's semi-final at the Athletic Grounds.