Relegated from AIB League Division One, Andy Ward's Belfast side will defend their cup title without lock Lewis Stevenson who is on Magners League duty with Ulster.
'Quins forwards Stevenson, who would have been available to play in the final due to his development contract status, and John Andress, the former Ireland Under-21 prop, are both leaving these shores to play for English side Exeter next season.
Harlequins beat Ballymena 26-13 in March's Ulster Senior Cup semi-finals, while Dungannon ended Malone's run with a 26-10 defeat. The final, which was due to take place last month, was postponed until tonight, "following a request by the sponsor."
The change of date allows the game to go ahead at the home of Ulster Rugby, as Ravenhill was being used as a venue for the IRB Under-19 World Cup last month.
Entry to tonight's Ulster Senior Cup final at Ravenhill is STGÂ£7 for an adult and Â£3 for children and parking is on a first come first served basis. Gates will open at 6pm.