The injury-hit Westmeath hurlers will be playing in the Christy Ring Cup next season after being relegated by Dublin in a 0-16 to 0-08 defeat in Tullamore.
Helped by a 0-08 (5f) contribution from David Curtin, the Dubs retained their Liam McCarthy Cup status in stifling heat.
Dublin roared into a 0-11 to 0-02 interval lead. Westmeath hit seven wides in the first half with Andrew Mitchell scooping over two frees.
The Lakesiders cut the gap to six points, but could not get closer. In a fiery finish, Dublin had wing-forward John McCaffrey (second yellow card) and full-back Kevin Ryan sent off, while midfielder Enda Loughlin walked for Westmeath.
In front of just 600 spectators at O'Connor Park, Mitchell arrowed over a second-minute free to put Westmeath in front for the first and only time.
Mitchell grabbed his side's only other point in the first half, also a free, on 17 minutes as Dublin, with captain Philip Brennan switching effortlessly between the right and left corner-back berths, turned their defensive domination into a string of points.
They cut loose for a nine-point interval lead with Curtin firing over five points. He grabbed a quick brace, the second set up by a beautifully timed hand-pass from John Kelly, to send the Dubs into a fifth-minute lead.
Fast ball in paved the way for Kevin Flynn, McCaffrey, Stephen McDonnell (0-2) and Michael Carton to send over a flurry of scores before the break. In between, Curtin chiselled further into Westmeath's spiralling confidence with a succession of frees.
Derek McNicholas was sprung from the Westmeath bench, just 16 minutes in, as Qualter sought a remedy but Dublin goalkeeper Gary Maguire continued where he left off against Limerick last week by impressively denying the substitute from 10 yards out.
With temperatures nudging towards 30 degrees and a nine-point deficit to overcome, Westmeath had it all to do. They did restore some pride by tugging the Dubs back.
Two points in the space of 20 seconds from McNicholas – the second straight from a poor puck-out from Maguire – cut the gap to 0-12 to 0-06.
Just moments later, Maguire did enough to put the lively McNicholas off when he tried to flick in a much-needed Westmeath goal, and with that, efforts waned on both sides with the heat taking its toll.
Dublin ended Westmeath's short spell of dominance with the athletic McCaffrey, who captain the Metropolitans' minors to Leinster glory last summer, moving to midfield and McDonnell switching into the half-forward line.
McCaffrey then turned villain when he walked for his second bookable offence with 15 minutes remaining.
When Westmeath needed a comeback all they could muster were two further frees from top scorer Mitchell. Kevin Flynn showed well in the closing stages, moving to midfield and catching a high ball for Curtin to turn and fire over.
A deft touch from Flynn also found substitute Peadar Carton for Dublin's final point. By that stage, Westmeath had already lost Loughlin to a straight red card. With the heat getting to everyone, a sizeable melee in the 68th-minute saw Ryan somewhat harshly sent off and Westmeath substitute Blaine Lahart getting away with a yellow card.
Dublin had the last laugh though and revenge for May’s Leinster SHC quarter-final defeat.
Dublin: G Maguire; G O'Meara, K Ryan, P Brennan (capt); M Carton (0-01), R Fallon, T Brady; D Sweeney, S McDonnell (0-02); J McCaffrey (0-02), L Ryan, D Curtin (0-08 (5f)); J Kelly (0-01), K Flynn (0-01), A McCrabbe.
Subs used: D O'Reilly for O'Meara (38 mins), P Carton (0-01) for McCrabbe (55), P O'Driscoll for McDonnell (66).
Westmeath: M Briody; C Jordan, C Murtagh, P Greville; G Gavin, J Shaw (capt), N Gavin; E Loughlin, A Mitchell (0-05 (5f)); B Smyth, B Murtagh (0-01), P Clarke; D Devine, D Carty, J Clarke.
Subs used: D McNicholas (0-02) for J Clarke (16 mins), B Lahart for Devine (half-time), T O'Keefe for P Clarke (half-time), M McNicholas for Smyth (51), M Williams for Carty (59).
Referee: Diarmuid Kirwan (Cork)