Aberdeen slipped seven points behind second placed Rangers in the Premiership with this defeat.
The Dons have endured a torrid time recently but presumably had not foreseen this latest failure, albeit County are now unbeaten in six Premiership matches.
However, Aberdeen had no grounds for complaint after substitute Ryan Dow headed the winning goal two minutes from time for County, who had Dutch defender Kenny van der Weg red-carded for a reckless 82nd-minute challenge on Jonny Hayes.
The early fast tempo augured well but as the pace of play gradually slackened so too did the accuracy of passes and constructive play.
While there was little to divide the sides in terms of possession, County created the better openings and twice had chances to take the lead before Hayes threatened the home goal with a viciously dipping free kick in the 23rd minute.
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Perhaps if Christopher Routis had shown a touch more composure in the sixth minute his speculative shot would have found the target instead of going wide.
Tony Dingwall was much closer to scoring two minutes later when Joe Lewis was fortunate to block the midfielder’s shot before the follow-up was scrambled clear.
The way Dingwall was able to get in behind the defence served as a reminder to Aberdeen of the need to tighten up at the back or risk being undone by his and Michael Gardyne’s pace.
It was in fact Gardyne who had the presence of mind to drag two defenders wide before releasing the ball to Liam Boyce in space in the 26th minute.
The Northern Ireland international was left with a relatively straightforward task in scoring from five yards but it is a measure of his contribution that he has now scored 41 goals in 93 appearances.
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Aberdeen should have drawn level in the 33rd minute but James Maddison was extremely wasteful when he slid in at the at the back post to make contact with Graeme Shinnie low cross but steered the ball wide.
Such profligacy can often prove extremely costly and it might have done had Lewis not then saved a shot from Craig Curran.
Not to be outdone, Scott Fox upstaged Lewis shortly before the interval when he threw himself to his left to keep out a Kenny McLean free kick from 25 yards.
The frantic nature of the early second-half play was characterised by a series of rushed moves and untidy finishes before Anthony O’Connor conjured up a long-range shot out of nothing and threatened to strip a coat of paint off the crossbar.
Having sensed a need to create greater stability in attack, Derek McInnes, the Aberdeen manager, replaced Wes Burns with Niall McGinn in the 52nd minute and was rewarded for his perceptiveness when the Irishman provided the equaliser.
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County’s failure to be alert to the danger posed by Shay Logan allowed the full-back to find McGinn with a pass and the striker duly netted from inside the box with 68 minutes played. But with the defence surprisingly static and County a player short, Dow converted fellow substitute Jonathan Franks’ cross from the right for a dramatic victory.
Star man: Andrew Davies (Ross County)
Ross County: Fox 7, Fraser 6, Quinn 7, Davies 8, Van der Weg 6, Dingwall 6 (Dow 58min, 5), Chow 6, Routis 7, Gardyne 6 (Franks 66min, 5), Curran 6 (Schalk 76, 5), Boyce 6
Aberdeen: Lewis 6, Logan 6, O’Connor 7, Considine 6, Shinnie 6, Hayes 6, Jack 6 (Storey 86min, 5), Maddison 6, McLean 6, Burns 6 (McGinn 52min, 5), Stockley 6 (Rooney 61min, 5)