Aaron Muirhead's 89th-minute penalty settled the match
A late penalty consigned Ross County to defeat in Tony Docherty's first match in charge as Arbroath moved level on points with Scottish Championship leaders St Johnstone.
Findlay Marshall's half-volley in the first half was straight at County goalkeeper Ross Laidlaw before Nikolay Todorov headed the visitors in front from Craig Watson's cross.
Akil Wright came close to levelling for Ross County when his header collided with the crossbar.
The hosts were awarded a spot-kick following a handball by Watson and Kieran Phillips converted.
Laidlaw blocked Taylor Steven's volley and County's James Scott fired over as both sides chased victory.
The decisive passage of play involved Declan Gallagher fouling Jacob MacIntyre and Aaron Muirhead striking successfully from 12 yards to secure three points for Arbroath.
The Staggies remain bottom of the table on two points, level with an Airdrieonians side that have played a game less.
