As County consolidated second place, Partick Thistle fell to third bottom and the boos echoed around the ground at the end.
County were ahead in 14 minutes when Josh Mullin burst in from the right and after his first shot was blocked by Sean McGinty he followed up to sweep a left-foot shot past Jamie Sneddon.
Thistle had some decent spells of possession but a lack of creativity killed them and County were happy to counter.
The Highlanders found a crucial second goal 11 minutes into the second half. Christie Elliott used an arm to block Ross Draper’s header after Mullin had crossed from the right and Nick Walsh pointed to the spot. Billy Mckay expertly tucked away the penalty.
The down side for County was Draper being sent off in the final minute for a second yellow-card challenge when he brought down Stuart Bannigan.