Cian Boland's point with two minutes remaining was crucial as Dublin edged out Westmeath to advance to the Leinster U-21 HC final on a 2-08 to 0-13 scoreline in Mullingar.
They will now meet defending champions Wexford in the decider on 9 July after the Slaneysiders ran out convincing 2-17 to 0-13 winners over Offaly in their semi-final at Wexford Park.
Colm Cronin, who is part of the senior panel, goaled for Dublin inside the first ten minutes to give them a 1-3 to 0-02 advantage . However, Westmeath responded with four unanswered points to level matters. Another flurry of white flags for the Lakesiders left it all square again - 1-06 to 0-09 - at half-time.
Boland, a half-time replacement for Caolan Conway, scored Dublin's second goal on 42 minutes to push them clear again. The spirit of the home side was again to the fore and Niall O'Brien fired over four points to restore parity.
O'Brien was hauled down in the box after 56 minutes and Westmeath were awarded a penalty. The same player stepped up to take the placed ball but his effort was saved by Dublin goalkeeper Conor Dooley.
It was then left to Boland to fire over the what turned out to be the winning score.
Wexford were never troubled by Offaly, despite having corner-back Garrett Foley sent off for an off the ball incident after only eight minutes.
The Faithful were also reduced to 14 men when full-forward Sean Dolan saw red in the second minute of added time at the end of the first half.
Conor McDonald and Rhys Clarke rose green flags for JJ Doyle's side in the opening period and they went in at the break leading 2-09 to 0-02.
Offaly did make a game of it on the resumption, adding 0-11 to the tally. However, Wexford were never going to be denied and now stand 60 minutes away from consecutive U-21 provincial titles.