St Patrick's Maghera earned a 1-10 to 0-11 replay win over St Colman's to set up a MacRory Cup decider with first-time finalists St Paul's Bessbrook.
Danny Tallon hit Maghera's goal after just three minutes before scores from Dara Noonan and Jack Haughey (two) helped the Newry school draw level.
However, Maghera reasserted themselves to lead 1-5 to 0-6 at half-time.
Maghera stayed ahead before Noonan blazed a penalty over the bar when a goal would have put Colman's ahead.
Haughey finished on seven points for Colman's but Maghera held on to set up the 18 March decider against competition new boys Bessbrook.
Maghera scorers: D Tallon 1-2, G Bradley 0-4 (3f), P Cassidy 0-2, J Kearney (f), S O'Hara (f) 0-1 each.
Newry scorers: J Haughey 0-7 (5f), D Noonan 0-3 (0-1 pen), J Fegan 0-1.