McKay's dismissal after the hour mark had Victory on top, and Mitch Austin put them ahead seven minutes from time by lashing home a loose ball.
Victory were set for three points on Friday night until a late set-piece was bundled home at the death, sparking frenzied celebrations from 15,805 at Suncorp Stadium.
The goal was miraculous, with DeVere volleying over a stranded Lawrence Thomas while falling backwards.
But in his first A-League start in 18 months after battling thigh and knee injuries, it was tough to begrudge DeVere his goal or the Roar their point.
McKay received yellow cards either side of half-time and was sent off in his 200th A-League game.
After receiving a first-half caution for swinging an arm at Fahid Ben Khalfallah, McKay earned his marching orders for tugging the Tunisian international's shirt on 65 minutes.
The skipper couldn't believe his fate, throwing his armband in referee Shaun Evans' direction as his incensed coach John Aloisi remonstrated from the touchline.
It allowed Victory to wrest back control of the match, which had failed to hit any great heights until then.
The most interesting battle was that of the two Socceroos' No.10s; A-League debutant Brett Holman and returning Victory midfielder James Troisi.
Holman hit the ground running with a sparkling display, finding space and directing traffic in the Roar's front third.
Troisi was bright but unable to link up effectively with teammates who weren't at the club when he left two seasons ago.
But he did create the best chance of the first half from a wide free kick, which debutant defender Alan Baro headed over from close range.
Holman spurned a similar chance from milestone man McKay's cross on 33 minutes.
A man down, Brisbane gave up the ascendancy but looked set for a point.
That is, until Austin reacted quickest when Ben Khalfallah's set piece bobbled from an aerial contest.
Given their last visit to Suncorp Stadium - when the Roar found two goals at the death in last year's elimination final - Victory were wise to be watchful until the final whistle.
But they were stung again, with substitute Leigh Broxham fouling Maclaren, allowing DeVere to capitalise on Tommy Oar's set piece.