Lisburn Distillery produced their best home performance of the season to put themselves within three points of Premiership safety.
A win over Dugannon Swifts on Saturday would see them safe for another season in the top flight.
Scott Davidson struck late in each half, with Gary Liggett on target in between those goals as the Whites won in style.
The first-half started off as a low key affair; DC threatened with a couple of half-chances, but it was their goalkeeper Robert Robinson who made two good saves in the 15th minute. He blocked Sean McCashin's close range shot from a corner and just seconds later he tipped over a rasping 20 yard drive from David Cushley.
Distillery goalkeeper Billy Brennan made his only real save on 28 minutes to clasp a Sean Cahill effort before the home side had another good chance on 37 minutes. Pat McShane’s cross was headed with by Cushley.
It was from another McShane cross that the Whites made the breakthrough in added time at the end of the first half. The ball zipped across the area and Scott Davidson, unmarked at the back post, wasted no time in drilling a shot past Robinson.
Liggett hit the side-netting and on 61 minutes before hitting his 22nd of the season 11 minutes later when he headed home Cushley's free-kick from inside the six yard box.
And to reinforce their dominance, Davidson steered home his second in the 93rd minute when he latched on to Jordan Hughes low cross.
Lisburn Distillery: Brennan, Callaghan, McCashin, Hunter, McShane, Davidson, Thompson, Kilmartin, Cushley (Hughes 73), Gawley (Liggett 52), Larmour (Gardiner 79). Subs: McCullough, Simpson.
Donegal Celtic: Robinson, Keegan, McNamee, O'Hara, Harkness, L Bradley, Devine (O'Connor 73), McAlorum, McAllister, Cahill (Henderson 59), Murray. Subs: McVeigh, Cunningham, P. Bradley.
Referee: Andrew Davey (Bangor).