The defiant Dingwall men had lost an equaliser by the time Dutchman Kenny van der Weg was sent off for a late challenge on Jonny Hayes. But former Dundee United man Dow sprang from the bench to send a winning header into the net in front of a stunned Dons faithful in the County north stand.
The result leaves the Dons seven points behind Rangers – and 18 behind leaders Celtic.
Derek McInnes, had a fully fit squad to choose from but left Adam Rooney on the bench, with Jayden Stockley favoured in the lone striker’s role, and Jonny Hayes and Wes Burns patrolling the flanks. Niall McGinn again started on the bench.
The hosts made one enforced change, with suspended Jay McEveley dropping out for fit-again captain Paul Quinn.
Aberdeen made a lively start, but County’s Christopher Routis flashed the first chance wide with a 20-yard attempt after six minutes. Routis and Liam Boyce then linked and the Northern Irish striker teed up young Tony Dingwall for a strike parried by keeper Joe Lewis. Dingwall was first to the rebound, but Anthony O’Connor forced a corner.
Kenny McLean’s dig from distance had to be pushed wide of the post by home keeper Scott Fox after 21 minutes as the Dons started to exert some pressure.
Boyce’s foul on James Maddison a minute later to the far right of the box posed fresh problems. Hayes’ left-foot delivery from the tight angle veered in powerfully at Fox but the keeper punched over the bar for a corner. From the Maddison corner, Andrew Considine glimpsed goal but his header was clutched by Fox.
McLean then sent a 35 yard strike dipping just over the County bar, but the home side were celebrating the lead after 26 minutes.
Boyce’s strength and intelligent movement had already troubled Aberdeen and his timing and awareness sealed the breakthrough.
Dingwall’s work on the right sparked the move and Routis, just outside the area and square on goal, fed Gardyne to the left. Gardyne made the right choice in firing a low, angled ball across the box and Boyce gave it the subtlest of helping hands to re-direct the ball past Lewis.
The action was relentless towards half-time. Gardyne surged into the Aberdeen box only to be thwarted by Lewis.
Graeme Shinnie was granted far too much space on the left for the Dons but his dangerous ball across somehow eluded Maddison in a great position.
McLean, a constant threat, then swerved a superb free-kick around and over the wall only for Fox to pull off a brilliant diving save low at the bottom left corner of his post.
Eight minutes into the second half, McInnes threw on McGinn for Burns. Soon after he took off Stockley and introduced Rooney, and on 68 minutes Aberdeen had their equaliser.
Shay Logan’s low supply in from wide right of the box was dummied by Rooney to leave the County defenders flailing. At the back of the penalty area, there was fellow substitute McGinn to drill low past Fox.
It was seemingly advantage Aberdeen when Van der Weg was red-carded for a late foul on Hayes that didn’t seem to merit such hefty punishment. But, to their huge credit, County came again.
With two minutes left, substitute Jonathan Franks’ cross was headed downward by defender Andrew Davies and then met by substitute Dow’s head. With the Dons defence mesmerised, the ball spun into the corner of the net – and County were left celebrating a much-craved victory.