After dethroning holders Wexford a fortnight ago, the Dubs qualified for their first final since 2014 and will play the winners of Offaly and Carlow in the decider.
Ultimately, it was the scoring contribution of Chris Bennett that proved the difference by the final whistle with the Faughs player excelling, in addition to landing two sublime second-half goals.
The hosts suffered a setback in advance of the throw-in with Shane Barrett ruled out through injury but they managed to open the scoring thanks to a 1st-minute point from Seán Ó Riain.
However, a number of errors punctuated their early play as Westmeath took advantage to level matters through a glorious sideline ball from Niall Mitchell.
Despite AJ Murphy restoring Dublin’s lead in the 7th minute, the visitors assumed control thanks to successive points by Jack Galvin, Darrgah Clinton and Ciaran Doyle.
Ó Riain spurned a gilt-edged chance of netting in the 12th minute as he fired off the crossbar following excellent approach play from Chris Bennett and that miss proved especially costly 30 seconds later as Doyle was on hand to kick home after an error by James Madden.
The hosts responded through points by Colm O’Neill, Murphy and Bennett but Westmeath were allowed to reply in kind through Clinton and Mitchell as they restored their four-point lead by the 20th minute.
The introduction of Cian Boland added a degree of pace and physicality to the home attack with Dublin finishing the half in the ascendancy through scores by Bennett, Boland, Murphy and Paul O’Dea as they entered the break enjoying a narrow 0-10 to 1-6 interval advantage.
The visitors once again impressed at the outset of the second-half thanks to a brace of frees from Doyle with a Bennett free leaving the sides deadlocked.
The contest turned in Dublin’s favour in the 40th minute when the lively Bennett eluded the clutches of Alan Cox before he unleashed a rising shot beyond Sean Maher from 12 yards. Bennett’s second goal arrived nine minutes later with his fierce shot once again dumbfounding Maher as the hosts eased home thanks to late points from Ó Riain and Boland.
C Bennett 2-6 (0-4f), AJ Murphy, C Boland 0-3 each, S Ó Riain 0-2, S Treacy (f), C O’Neill, P O’Dea 0-1 each.
C Doyle 1-7 (0-5f, 0-1 ‘65’), D Clinton 0-3 (0-2f), N Mitchell 0-2 (0-1 sideline), J Galvin, W Casserly 0-1 each.
J Treacy; E O’Donnell, J Madden, C Hendricken; M McCallion, C Mac Gabhann, P O’Dea; J Malone, J Bellew; E McHugh, AJ Murphy, S Treacy; C O’Neill, S O Riain, C Bennett.
C Boland for McHugh (19), R McBride for McCallion (39), F Ó Riain Broin for O’Dea (41), S Gray for Murphy (46), B Bolger for Bellew (56).
S Maher; A Cox, C Shaw, M Heeney; J Rabbitte, L Varley, R Gillen; W Casserly, K Doyle; D Egerton, L Cassidy, N Mitchell; J Galvin, C Doyle, D Clinton.
P Scally for Cassidy (half-time), D Giles for Cox (42).
Barry Redmond (Wexford)