The All-Ireland SFC final was evenly poised for 45 minutes before McKay ventured forward and got on the end of a handpass from Stefan Campbell before palming the ball to the net, giving Armagh an advantage they would not relinquish despite a nervy finish.
Galway will live to rue a string of second-half wides, however, as they left behind enough chances to win the game, let alone force a draw, but it was Armagh’s day at GAA HQ as Croke Park turned orange for the day.
The first half certainly didn’t live up to the hype with little of major discussion in a half where safety was key for both sides with a reluctance to cough up any goal-scoring chances.
The major talking point of the first 35 minutes was the departure of Galway attacker Rob Finnerty after only 11 minutes after a heavy collision when winning an early free that he converted.
Galway settled the better and opened up a 0-3 to 0-1 lead with Liam Silke and Paul Conroy firing over, but Oisín Conaty and Ben Crealy were in similar form at the other end as they levelled it up.
The sides would share the next six points from there until the break, including savage scores from Armagh defenders Aidan Forker and Barry McCambridge, and it was all to play for going down the tunnel, 0-6 apiece.
The game exploded to life immediately after the resumption with Conroy kicking his third point from play, another brilliant long-distance effort, but Conaty and Rian O’Neill were equally as good at the other end with fine scores.
The sides were level again after 42 minutes when Tiernan Kelly kicked over, 0-9 each, but the game turned in the Orchard men’s favour five minutes later with McKay slamming the ball to the net in emphatic fashion.
Armagh had the lead out to as much as three points with Niall Grimley and Oisín O’Neill adding fine scores, 1-11 to 0-11, but they were made sweat down the home straight.
The brilliant Céin Darcy, who finished with three points, and Cillian McDaid left the minimum in it after they ended a 14-minute spell without a score but try as they might, they couldn’t get the ball over the bar and force extra-time.
It was all about Armagh as McGeeney, captain for their first triumph in 2002, led his troops to the promised land before a sea of emotion erupted in Croke Park.
SCORERS – Armagh: A McKay 1-0, O Conaty 0-3, B Crealey 0-2, A Forker, B McCambridge, R O’Neill, T Kelly, O O’Neill, N Grimley 0-1 each.
Galway: P Conroy, C Darcy 0-3 each, C McDaid, S Walsh (1f) each, J Maher, L Silke, R Finnerty 0-(f) 0-1 each.
ARMAGH: B Hughes; P Burns, A Forker, B McCambridge; Connaire Mackin, T Kelly, A McKay; N Grimley, B Crealey; J McElroy, R O’Neill, O Conaty; R Grugan, A Murnin, C Turbitt. Subs: S Campbell for Turbitt and R McQuillan for Kelly (both 46), O O’Neill for Grugan inj (51), J Burns for Mackin (59), J Duffy for Forker (75).
GALWAY: C Gleeson; J McGrath, S Fitzgerald, J Glynn; D McHugh, L Silke, S Mulkerrin; P Conroy, M Tierney; J Maher, D Comer, C Darcy; R Finnerty, S Walsh, C McDaid. Subs: J Heaney for Finnerty inj (11), S Kelly for Glynn (45), T Culhane for Comer and D O’Flaherty for Tierney (both 66), K Molloy for Heaney (75).
REF: S Hurson (Tyrone)