Kiss opened the scoring with a first-half header before Frenchman Yoann Arquin's point-blank strike in the second half gave County a two-goal lead.
Cardiff City loanee Kiss then made it three for the home side with a stunning 35-yard strike that ensured United's winless run continued to six matches.
Farid El Alagui, on-loan at United from Brentford, had the game's first opportunity but his long-range shot was saved by Michael Fraser.
Ross County duo Graham Carey and Jordan Slew both had left-footed efforts from distance saved by Radoslaw Cierzniak before El Alagui again went close for the visitors but his header was straight at Fraser.
County enjoyed the majority of possession during the first half and were rewarded for their dominance just before half-time after Kiss' effort was put out for a corner by Andrew Robertson.
Carey swung the ball in and Kiss rose highest to power his header past Cierzniak and put the home side in front.
The away side tried to take the game to County in the second half with El Alagui, Gary Mackay-Steven, Nadir Ciftci and John Rankin all having unsuccessful efforts from distance.
But County doubled their advantage on 69 minutes when debutant Yoann Arquin, on-loan from Notts County, made no mistake from close-range after being played in by Jordan.
Things went from bad to worse for United when Kiss scored a goal worthy of winning any game when he smashed the ball into the top right-hand corner from all of 35 yards.
Ten minutes from time, Evangelos Ikonomou almost made it four for County with a left-footed shot that Cierzniak got down well to save.
With five minutes left to play Calum Butcher almost added a touch of respectability to the scoreline but his effort went narrowly wide as United's barren run continued.