McGilloway replaced Beau Cornish in the latter stages and his deflected effort minutes from full time sent the Wingmakers into pandemonium.
Adam Davies was stretched off in the second half after suffering a serious injury - a sad moment in what was an otherwise perfect night (everyone at the club wishes Adam a speedy recovery).
The boss made two changes to last weekend’s starting line up that won at Prestatyn. Experienced duo Gaz Edwards and Simon Spender both returned in defence.
In front of the Sgorio cameras, it was the visitors - needing a victory to remain in the title race - who started quickest in Broughton.
Lee Thomas capitalised on a mix up in the Airbus backline but Lewis Dutton produced a fantastic save to prevent Llandudno registering an early lead.
In the ninth minute, the Seasiders were once again probing. This time, Gareth Evans’ header rebounded off the crossbar following a well delivered corner.
After a slow opening, the Bus soon found their usual groove and created a golden opportunity. Davies danced by two players and unleashed a thunderous strike inside the area; only a neat Shaun Pearson saved denied the goal hungry forward.
Jay Crowther tried is luck from range on two separate occasions as O’Shaughnessy’s men searched for a breakthrough before the break.
However, as the half time whistle blew, both teams knew a clinical edge was needed to convert chances in the second period.
The intensity of the contest increased from the outset in the final 45 minutes. George Peers received a yellow card for a late tackle as the youngster showed slight over exuberance.
Peers then burst beyond his marker on the left flank but was unable to find a decisive pass when he reached the final third.
With 15 minutes to play, the importance of the top of the table encounter quickly paled into insignificance. Davies was fouled by G.Evans who was shown a straight red card and the Cymru North’s leading goalscorer was stretched off - it should be noted there was no malicious intent in Hughes’ tackle.
Nathan Brown - who had been brought on to replace Peers in the 70th minute - was causing problems for a tiring Llandudno side with his blistering pace after the game restarted following a lengthy stoppage in play to treat Davies.
In the 87th minute, Brown came inches away from firing the Wingmakers ahead in style. His long range dipping hit had Pearson scrambling but the ball narrowly sailed over the bar.
With nine minutes of injury time to play, Airbus kept plugging away and were eventually rewarded by the man who has featured sparingly this season due to injury.
McGilloway shifted the ball out of his feet on the right side of the box and fizzed a shot towards goal that deflected into the Seasiders' net.
The full-back ensured Airbus were crowned champions with three league matches still to play - a fitting ending after Davies' earlier misfortune.
Airbus will now return to the JD Cymru Premier should Tier One licensing be granted. The trophy presentation will take place at the conclusion of the Bus' final home game of the season on April 15 against Gresford Athletic.
What a season this has been!