Captain Reuben Murray struck the killer goal as Longford produced a terrific second-half display to regain the Lory Meagher Cup title.
Trailing by two points at half-time, Longford produced a brilliant half of hurling to firstly reel in neighbours Leitrim and then dominate them.
Murray's 52nd-minute goal was the crucial score as it put Longford into a lead they held onto, securing their third title at the grade and first since 2014.
Murray finished with 1-03 and was among a team of solid performers that included former Limerick senior Cathal Mullane, who sniped 0-03, centre-back Martin Farrell and Maitiú O'Donohoe.
The five-point win has secured Longford's promotion to the Nickey Rackard Cup for 2027, capping a great season having already gained promotion from Division 4 of the Allianz Hurling League.
But it's the end of the road for Leitrim who had a bright first half but faded out and lamented their nine second-half wides when the game was in the melting pot.
Leitrim blitzed the group stage of the competition, taking five wins from five to secure a spot in their first national decider since 2019.
But they took their time to get going on the grand stage, falling two points down after the opening quarter, 0-02 to 0-04.
Three Longford points in a row from O'Donohoe helped Longford to maintain that narrow advantage with 27 minutes on the clock, 0-08 to 0-06.
But Leitrim finished the half strongly, reeling off four points without response and conjuring a couple of goal chances that Kevin Clerkin was unable to convert.
Colm Canning struck the last two points of the half for the Connacht side, the first off his right from beneath the Hogan Stand, the second a terrific effort off his left side from a central position 50 metres out.
Leitrim were good value for their 0-10 to 0-08 half-time lead and aside from the Clerkin goal chances, wing-forward Paul Mulligan also had an effort that was well saved by Johnny Maher.
Playing his club hurling with Kilmacud Crokes in Dublin, Maher kept Longford in it with three first-half saves in all though they were frustrated at the other end by seven wides.
The third quarter was a forgettable period, the sides splitting four points evenly between them.
Longford had a great chance to take the lead in the 51st minute but David Buckley and substitute Stephen Murray were both denied by Clement Cunniffe saves.
The Leinster men still conjured a Paddy Lynam point from that move and got the goal they craved a minute later when Murray pounced from close range, doubling on a long delivery that bounced in the danger area.
Clearly energised and high on adrenaline, Murray, wearing number eight but operating at full-forward, followed up with a cracking point from in front of the Cusack Stand into the Davin End.
Leitrim had enough possession to haul themselves back but wasted too much of it, blasting a series of wides which allowed Longford to lead 1-13 to 0-13 with eight minutes remaining.
Longford proceeded to reel off five unanswered points from there, including two from Mullane, giving themselves a vital cushion to absorb the concession of a Joe Murray goal for Leitrim right at the death.
Longford: Johnny Maher; Ciarán McNally, Seán Lancaster, James Connell; Johnny Casey, Martin Farrell (0-04, 0-04fs), Evan Tully; Reuben Murray (1-03, 0-01f), Paddy Lynam (0-02); Maitiú O'Donohoe (0-03), Ronan Courtney (0-01), Cathal Mullane (0-03); Joe Rabbitt (0-01), David Buckley (0-01), Micheál Mulcahy.
Subs: Eamonn Allen for Courtney (33), Seán Tiernan for O'Donohoe (44), Stephen Murray for Rabbitt (47), Niall Hawes for Murray (68), Kealan Cox for McNally (72).
Leitrim: Clement Cunniffe; Paul Lenehan, Conor Hackett, Pearse Kenny; Niall Crowe, Martin Feeney, Joe Murray (1-00); Philip Burgess (0-03), Stpehen Goldrick; Paul Mulligan (0-02), James McNabola (0-01), Kevin Clerkin; Dhani Keane (0-01), Colm Canning (0-04, 0-01f, 0-01 65), Gavin O'Hagan (0-02).
Subs: Mark McHugh for Clerkin (61).
Referee: Conor Daly (Kildare).
