Goals from James McFadden and John Sutton early in the second half should have seen the Fir Park side on their way to a comfortable win but a Yann Songo'o strike eight minutes from time had the home side hanging on nervously for their second home win of the week over Highland opposition.
Prior to the 2-1 success, County boss Derek Adams had pinpointed defensive weaknesses in the Motherwell set-up - but it was not until his side fell two goals behind that the Highlanders really threatened.
Until then the visitors were content to give Well possession until they reached the County third of the pitch, where they found it difficult to find gaps to turn into goal chances.
Top scorer Sutton looked frustrated with the defensive marking and his first effort on goal after 12 minutes was a left foot drive from 20 yards which was always rising over the target.
Little was seen of County in an attacking sense until Richard Brittain's inswinging free-kick enticed Gunnar Nielsen to leave his line and clutch the ball in a packed six-yard box.
Then, with only the goalkeeper to beat, Jordan Slew slammed his shot wide of the post.
Motherwell's main threat came from set-pieces and Lionel Ainsworth's corner picked out Shaun Hutchinson, who powered his header just wide of goal.
On the half hour, former Well goalkeeper Mark Brown was forced into his first save.
Hutchinson hoisted a free-kick into the box and Iain Vigurs found the unmarked James McFadden - but as he tried to lob the ball into the net, the goalkeeper produced a good one-handed save.
McFadden was denied again eight minutes later when Steven Hammell's cross found him at the back post but as the former Scotland striker tried to squeeze the ball inside the post Brown reacted superbly to block the effort.
However, McFadden was not to be denied a third time as Motherwell opened the scoring two minutes into the second half.
Former County player Vigurs latched onto Stuart Carswell's lay-off before unleashing a terrific 25-yard drive which Brown could only parry, allowing McFadden to stroke the ball past the grounded keeper to make it 1-0.
Brown then prevented it becoming 2-0 when he beat away another stinging drive from Vigurs after Hutchinson had raced upfield to set up the midfielder.
The County keeper looked less certain when he took two attempts to gather McFadden's low free-kick as the home side pushed for a second goal to kill the game.
After 55 minutes and having grabbed the opener McFadden made way for 19-year-old striker Craig Moore.
And the substitute set up Well's second goal on the hour when his swerving shot was palmed out by Brown to the waiting Sutton who, from six yards, guided the ball into the net via the underside of the bar for his 19th goal of the season.
Motherwell looked comfortable but in the 78th minute Brittain came within inches of getting his side back into the game when he side-stepped a couple of defenders before drilling his angled shot off the foot of the post with Nielsen beaten.
However with eight minutes remaining County pulled one back with a fabulous goal. Graham Carey floated over a corner and defender Songo'o met it full on the volley from eight yards to send the ball screaming high into the net.
That set up a nervous finish for the home side and Slew scooped over from close range before Arquin rifled a shot just wide of the post - but Well held out for a deserved three points.