Barry will now be at the Alexandra Palace twice at Christmas after last month also confirming his spot at the JDC World Championship final which will also be played at the showpiece event.
The 17-year old will take his place in the field after taking the chances given to him by his opponent who let a big opportunity go. The rise of 'Dynamite' continues.
Despite a good first few turns from Gallagher to start the tie, a 180 turned the first leg and allowed Barry to hold his throw with a 33 checkout.
Another 180 was hit by Barry but a 56 checkout saw Gallagher level proceedings up. After Barry busted his score though, Gallagher came back to the board and took out 64 to claim an early break.
He continued his good form so far by landing tops to lead by two with 3/4 on the doubles the real difference at this point.
Barry landed a fourth 180 and he hit an 82 checkout to go one behind but two 36 checkouts on the bounce saw Gallagher go one away in an impressive performance from 'The Tornado'.
Gallagher though squandered multiple match darts and Barry took out 96 to trail 5-3. In the following leg, it was further missed darts from Gallagher as Barry got off the hook to trail 5-4.
A tenth match dart went for Gallagher who saw his chances start to 'Slide Away' and Barry hit a 106 checkout to send it all the way.
It was 11 missed match darts by the end but Barry claimed the victory to confirm his spot at the 2020 PDC World Championship and win the historic Tom Kirby Memorial Irish Matchplay.
Tom Kirby Memorial Irish Matchplay
Final
Liam Gallagher (82.7) 5-6 (84.14) Keane Barry
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