Three late points from Sean Armstrong, Paul Conroy and Cormac Bane steered Galway to their 44th Connacht SFC title at Castlebar.
The Tribesmen tasted provincial glory for the first time since 2005 as they held off a fiery second half comeback from their arch rivals Mayo.
Goals from Padraig Joyce (21 minutes) and Fiachra Breathnach (28) had Galway leading by 2-04 to 0-06 at half-time.
With the fit-again Alan Dillon (0-07) in top-scoring form, Mayo quickly got back in touch and they managed to edge ahead in the 51st-minute when substitute Aidan Kilcoyne netted.
But, encouraged by that trio of points, Galway crucially had the better finish and Mayo's search for a late, levelling point was an unrewarding one as Conor Mortimer missed a 74th-minute free.
Meeting Galway for the seventh successive year in the championship, Mayo brought the fit-again Alan Dillon in as the only change to the team that secured them a memorable 3-11 to 0-07 semi-final win over last year's Connacht champions Sligo.
Galway, who beat Roscommon 2-16 to 0-06 last time out, drafted Niall Coyne, Diarmuid Blake, Barry Cullinane and Cormac Bane into their starting line-up for what was the 109th Connacht final.
Having won the toss, Mayo opted to play with the wind advantage but that move backfired on them as Galway, threading through some delightful 40-50 yard balls, continually sliced open their opponents' defence.
The inexperienced Colm Boyle and Kieran Conroy, only in their second championship outings, were ruthlessly exposed by Galway's quick-witted attack, while old hands David Heaney and James Nallen struggled initially to keep tabs on their men.
Mayo certainly had defensive problems but they were able to keep in the game thanks to the decision-making of Dillon and the Mortimer brothers up front.
They edged 0-03 to 0-02 ahead by the midpoint of the first half, with their scores coming either from frees or individual efforts rather than team-crafted attacks.
Galway hit the front in the fourth-minute when Nicky Joyce darted forward and won a free which Michael Meehan pointed.
Mayo were quickly back on terms when Dillon curled over a pinpoint free, two minutes later, as Galway made a flurry of positional switches at the other end.
The first clearcut goal chance followed in the ninth-minute when Nicky Joyce forces a good save from David Clarke, after his cousin Padraig Joyce had cleverly picked out Cormac Bane with a through ball.
Mayo, who used Trevor Mortimer as a third midfielder before injury cut short his afternoon, were struggling to up the gears at this stage.
Just moments later, Nicky Joyce again rampaged through the Mayo defence, he linked with Padraig Joyce but the team captain's left-footed shot was off target as he looked to test Clarke.
The game began to pick up pace as Trevor Mortimer accelerated through the Galway rearguad and pointed on the run.
Bane, set up by Niall Coleman and Meehan, replied from an acute angle at the other end before Dillon hit the post with a fisted effort.
A superb catch from Pat Harte from a kick-out led to a Conor Mortimer point. Mayo's lead lasted just two minutes as Padraig Joyce catapulted his side ahead with a quick 1-01.
The veteran forward fired over a great point off his left, into the wind, before scoring a wonderful individual goal.
He collected a loose ball 20 metres out from goal, rode a challenge from Tom Cunniffe and sent three Mayo defenders the wrong way before dispatching the ball to the bottom right corner of Clarke's net.
Galway were transferring their dominance onto the scoreboard as Bane, first to the ball again, lobbed over from the left.
A second goal followed for Liam Sammon's side, seven minutes before the interval, when the busy Matthew Clancy raced through Mayo's centre.
He was chopped down by Nallen but got up to continue his progress before Meehan fisted over to the left where Fiachra Breathnach was able to sneak a low shot to the net for his first championship goal.
Now seven points ahead, Galway looked to be coasting but three points from Mayo in the closing stages of the first half gave a preview of what was a fiercely contested second period.
Dillon landed a right-footed free, Mayo skipper Ronan McGarrity also pointed after a good right wing attack involving Aidan Kilcoyne and the increasingly influential Dillon thumped an excellent point over from the left to complete that run of scores.
Mayo boss John O'Mahony performed a considerable amount of surgery on his team in and around half-time, with Boyle and Conroy making way for Peadar Gardiner and Aidan Higgins.
In attack, both Kilcoyne and Billy Joe Padden were introduced to good effect and the switches seemed to have the desired effect, coinciding with a lull in Galway's play.
Mayo began to look the part on the resumption as Conor Mortimer got away from his marker Damien Burke to boot an excellent 37th-minute point.
Galway, who lost Clancy to concussion, responded with a Meehan free but Mayo continued to turn the screw with white flags from Dillon (0-02) and Padden.
In between, Galway's superb corner back Gareth Bradshaw, who turned in a man-of-the-match display after his move into the half-back line, fired over a fine right-footed point.
Dillon's fifth point after a foul by Burke on Mortimer made it a two-point game at 2-06 to 0-10 and Galway seemed to be wavering with Nicky Joyce hitting an horrific wide.
Mayo, having noticeably upped the pace, suddenly powered ahead.
A booming free from Dillon from the left slid off target and the ball, dropping to the right of the square, was broken down by Andy Moran for Kilcoyne to slot home, stunning Paul Doherty and the Galway defence.
It was Mayo's first goal against Galway in the championship since 2002 and looked to be the likely springboard to inspire then over the remaining 20 minutes.
Galway looked to their talismanic captain Joyce to draw them level with Mayo for the fourth and fifth time. Joyce's two points sandwiched a classy score from Mayo midfielder Pat Harte.
While Galway left a couple of goal-scoring chances behind them in the first half, Mayo almost doubled their goal tally on 60 minutes when Kilcoyne, set up by Dillon, squeezed a left-footed shot just inches wide of Doherty's goal.
In a tension-filled finale, Bradshaw teed up Meehan for a relieving point, shooting the Tribesmen ahead again at 2-09 to 1-11.
Padden linked with his fellow substitute Gardiner before tying up the game for the sixth time.
However, a quick Mayo attack led to another successful Dillon free after Paul Conroy, one of Galway's minor stars last year, was pinged for taking too many steps.
As the sides went tit for tat, Galway managed to break clear as they carved out the victory with three impressive points in as many minutes.
With his side 2-09 to 1-13 behind, Sean Armstrong succeeded in squaring up the game before Conroy fired over an excellent point off his right and Bane then brilliantly followed up with a skyscraper score from centre-field.
The two-point buffer gave Galway enough latitude to see out the win as they gleefully lifted the JJ Nestor Cup for the fifth time this decade.
Two minutes into injury-time, Dillon hit a close range free to close the gap to a single point but Galway stubbornly held their ground in the helter skelter final moments.
Scorers – Galway: P Joyce 1-03, F Breathnach 1-00, M Meehan (0-02f), C Bane 0-03 each, G Bradshaw, S Armstrong, P Conroy 0-01 each. Mayo: A Dillon 0-07 (0-05f), A Kilcoyne 1-00, BJ Padden, C Mortimer 0-02 each, T Mortimer, R McGarrity, P Harte 0-01 each.
Galway: P Doherty; G Bradshaw, F Hanley, D Burke; N Coyne, D Blake, G Sice; B Cullinane, N Coleman; C Bane, P Joyce (capt), N Joyce; M Clancy, M Meehan, F Breathnach.
Subs: K Fitzgerald (for Coyne 35+1 mins), S Armstrong (for Clancy h/t), P Conroy (for Coleman 54), M Lydon (for N Joyce 57), N Coleman (for Breathnach 70+3).
Mayo: D Clarke; K Higgins, K Conroy, C Boyle; T Cunniffe, D Heaney, J Nallen; R McGarrity (capt), T Parsons; A Dillon, P Harte, T Mortimer; C Mortimer, A O'Malley, A Moran.
Subs: A Kilcoyne (for T Mortimer 23 mins), P Gardiner (for Boyle 31), A Higgins (for Conroy 31), BJ Padden (for O'Malley 40), M Ronaldson (for Parsons 70).
Referee: David Coldrick (Meath).
