Dutch striker Kevin van Veen – who had come on as a substitute just four minutes earlier – won and scored a 68th minute penalty to earn the visitors just their second league win from 16 matches.
In so doing, van Veen took Motherwell up to fifth spot, two points ahead of sixth placed County with just two league games remaining this campaign.
If ’Well are still in fifth place come the end of the season, they will earn a spot in the second qualifying round of the Europa Conference League.
Saturday’s success in Dingwall was also notable from the point of view that it was only Motherwell’s second league win of 2022 and their first clean sheet in 14 matches.
Yet it was the hosts who looked the more likely team earlier on with Regan Charles-Cook having a shot blocked, Jake Vokins testing Liam Kelly from 20 yards and David Cancola shooting just over the bar.
Motherwell gradually grew into the game although both sides struggled to create clear-cut chances.
The away team’s best first-half opportunity came when Joe Efford's shot on target was turned wide by home goalie Ross Laidlaw and, from the resultant corner, Connor Shields nodded a close-range effort too high.
Cancola went close again for County in the second half as his curling attempt flew the wrong side of the upright, following fine build-up play down the left flank.
Kelly pulled off a wonderful save to keep the score level after Keith Watson had set up to Blair Spittal, and Motherwell capitalised with the game's defining moment.
Alex Iacovitti was penalised for his challenge in the box on Van Veen, who coolly sent goalkeeper Laidlaw the wrong way from 12 yards.
In a busy final week of the league campaign, Motherwell will host Hearts on Wednesday night with kick-off at 7.45pm before ending with a trip to Celtic Park this Saturday with kick-off at 12.15pm.