Manager Mickey McCann hailed Donegal's outside influences as players from Wexford, Tipperary, Tyrone and Armagh all combined to help secure the Nicky Rackard Cup title.
Tipp man Davin Flynn played a key role with two crucial interventions late on as Donegal, trailing by a point with 67 minutes on the clock, conjured an unanswered 2-1 to seal a memorable win.
Flynn, a former Tipperary minor and an intermediate for his county five years ago, firstly blasted home a goal to put Donegal two points ahead.
Then he played in the teasing ball that was like meat and drink to powerful full-forward Ritchie Ryan who snatched it from the air before spinning his man and smashing to the net.
Former Armagh regular Declan Coulter, a tournament winner with the Orchard, then added a point to secure a six-point win that left Mayo on their knees.
The westerners, who'd played in a division two tiers higher than Donegal in the League, had actually led by eight points after a terrific start but winced at the 14-point swing on the scoreboard by full-time.
Gerard Gilmore, from Tyrone, was also on the mark for Donegal with a point and it was his run and clever pass that freed Joe Boyle for their first goal while goalkeeper Luke White plays with the successful St Martin's club in Wexford.
"Declan Coulter played most of his hurling with Armagh and he's married to the sister of our midfielder Danny Cullen," said manager McCann. "He's living in Donegal for three or four years now and hurling with Setanta.
"He was one of Armagh's top players and he's a great addition for us. With Davin Flynn, he didn't actually play for us last year and he was a big loss. He's been carrying an injury for the last couple of weeks but he progressed well this week.
"He's a top class player, just top class. You know he's played at that better level than Donegal hurling and when you have boys like that on board it raises the standard.
"With Luke White, he's a schoolteacher in Donegal now in Inishowen beside myself. He's a super 'keeper and probably worth three to four points for us each day.
"You saw it today, another clean sheet and very, very comfortable on the ball and with the puckouts. These guys have all played at a good standard but they're enjoying their hurling in Donegal and they were surprised when they came up and saw the standard that hurling is being played at. They just bed in well with us."
Donegal required all of them to play their part because Mayo burst out of the traps and looked by far the slicker, crisper and sharper team.
Donegal full-back Stephen Gillespie was initially in real trouble on Brian Morley, fouling the Mayo full-forward twice for frees that were converted by Shane Boland. Eoin Delaney struck from open play for Mayo and also tempted Gillespie into a foul that was converted by Boland.
Free-taker Boland hit six points in total in the first 22 minutes and Mayo led by 0-11 to 0-3 at that stage. It felt like they were on the brink of blowing Donegal out of the water if they could snatch a goal.
A Boyle point appeared to settle Donegal though and they would tack on 1-5 before the interval to give themselves hope, Boyle also striking the goal just before the interval.
It wasn't the sweetest of strikes from Boyle and the 'keeper should probably have dealt with it but the ball deflected in and Donegal were right back in it, trailing 1-8 to 0-14 at the break.
Flynn scored back to back points from play early in the second-half as Donegal upped the ante and a three-in-a-row of converted frees from Coulter nudged the north-westerners two points clear.
Cathal Freeman got Mayo going with a couple of long range scores and with three minutes remaining, Donegal found themselves a point behind again.
That's when Gillespie, under pressure earlier in the game, came charging out of defence and released a long delivery that broke kindly for Flynn to snipe his goal. Ryan added another moments later and Coulter wrapped it up.
"It was worrying times after 10 or 15 minutes, Mayo looked like they were two or three levels above us but when we settled we got into the game," said McCann who bemoaned the lack of promotion for the Rackard winners.
"To keep the hunger, you'd have wanted to raise the standard up again and to compete in the Christy Ring, that would have been a key thing for us and to try to stay in that competition then."
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DAVIN FLYNN (DONEGAL)
The Roscrea man burst into life early in the second-half with two excellent points that gave Donegal hope. The first was a wristy, over the shoulder that highlighted his ability. A minor championship player for Tipperary 10 years ago, Flynn struck a crucial late goal and finished with 1-3.
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CATHAL FREEMAN (MAYO)
The experienced Mayo defender raised EUR60,000 for charity with a unique marathon run during the lockdown earlier this year and rose to the challenge again when his team needed him. It was Freeman's two long-range points in the closing minutes that left Mayo in the lead before Donegal's 2-1 burst.
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Donegal: L White; M Callaghan, S Gillespie, G Browne; M Donaghue, S McVeigh, J Boyle (1-1); C Mathewson, D Cullen (0-3); R McDermott (0-1), J O'Loughlin, K Kealy; D Flynn (1-3), D Coulter (0-9, 7f), G Gilmore (0-1).
Subs: R Ryan (1-0) for Kealy (29), B Lafferty for Mathewson (62), C O'Grady for Cullen (74).
Mayo: G Kelly; G Nolan, S Coyne, J Cassidy; B Hunt, D Kenny, C Freeman (0-2); S Regan (0-1), S Kenny (0-1, 1 65); A Phillips (0-1), S Boland (0-11, 10f), C Scahill (0-1); J Coyne (0-1), B Morley (0-2), E Delaney (0-1).
Subs: L Lavin for J Coyne (51), C Phillips for Delaney (54), D Huane for Hunt (64), S Mulroy for Morley (66).
Ref: K Jordan (Tipperary)
