United opened the scoring midway through the first half when Roddy MacLennan knocked the ball in from Fraser Keast.
Dundonald equalised straight from the kick off in the second half after John Millar was judged to have committed a foul in the box.
Ross Philp sealed the game for United with 15 minutes to go from an assist from Stuart Hunter.
In the final minute of the match Dundonald looked to have made it all even, however a wonder save from Darren Jamieson sealed the game for the home side.
Estimated crowd – 350