Finn Harps are heading back to the First Division - having missed out by a point on the final evening of the campaign.
Harps went into the game knowing that they had to win, while at the same time needing Galway United to slip up against UCD at Belfield.
But while they obliged in front of the Finn Park fans, UCD did them no favours.
Rovers gave Harps an early scare when a Padraig Amond shot was deflected into the side netting.
But on a muddy-surface reminiscent of 70s Famous Fried Chicken League of Ireland days, Harps showed their urgency in the first quarter.
Shaun Holmes let fly with long range drive that whizzed past the post and Marc Mukendi then unleashed a cracking effort that forced Barry Murphy into action.
Chris Breen was then denied by the Hoops custodian who, on 28 minutes, had to go full stretch to divert a Shaun Holmes curling free around the post at the expense of a corner.
However, revved up Harps broke the deadlock on 29 minutes when full-back Marc Mukendi scored only his second ever goal for the Donegal club as he struck with a shot that squirmed through a crowded goalmouth and into the net.
Five minutes later Conor Gethins darted through on goal. Murphy advanced to thwart him, but the striker made amends on 37 minutes as he capitalised on some suspect defending to slot in Harps' second.
Harps really should have added a third seven minutes after the break when Breen surged down the left and whipped in a cross for Mukendi, who somehow headed wide from about a yard out.
The home side continued to dominate, and Rovers endured a number of anxious moments. Danny O'Connor cleared a Declan Boyle effort off the line while Shaun McGowan and Gethins both went close.
Harps never looked like letting Rovers back into the game in the second half and goalkeeper James Gallagher, in his final game before retiring due to recurring injuries, was rarely tested.
Harps went off to a standing ovation, but overall it was a night of disappointment on Finnside.
Finn Harps: Gallagher: Mukendi, Boyle, Minnock, Holmes; Funston, McGowan, McCafferty, Breen; Parkhouse, Gethins.
Shamrock Rovers: Murphy: Madden, O'Brien, Price, Flynn; Doyle, D O'Connor, Rice, S O'Connor (Martin 62); Amond, Purcell (Leech 77)
Referee: Mr. D. Tomney (Dublin).
