Findlay Frye etched himself into Cumnock folklore with a 93rd minute winner as Brian McGinty's men lifted the Scottish Junior Cup for only the third time in their history.
The midfielder pounced deep into stoppage time following a tense final at Broadwood which had looked to be heading towards stalemate.
But his last gasp intervention sparked wild scenes of joy among the thousands of 'Nock supporters who made the trip to Cumbernauld to witness history tonight.
Both sides had emerged to a raucous atmosphere in front of more than 4,000 at Broadwood, with Cumnock's army of supporters ensuring it felt like a home game for McGinty's men.
But it was Rutherglen who almost hit the front with the game nine minutes old when Jack McIlveen burst into the box but his low left footed effort was saved by Jamie Barclay.
Cumnock struggled for early rhythm and a Findlay Frye shot which was blocked was as close as they came in the opening half hour of a tight contest.
Rutherglen looked a danger on the break and Sean McGuire snatched at an effort which he sent wide as they threatened to make the breakthrough.
Cumnock slowly began to exert more pressure and a Jared Willet free kick was headed back across goal by Kyle McAusland, only for Jordan Moore to miss out on the key connection six yards from goal.
Willet then sent an effort over from 25 yards after a lively run from the centre of the park before Greg Ferry beat Glencairn keeper Scott Law to a cross but saw his header drift just over the bar.
Cumnock had to make an early switch just after half time when James Dolan was replaced by Graham Boyd but they went close seconds later when Ferry headed wide from a Willet free kick.
The second half became a tense affair with chances at a premium before Cumnock stepped up a gear with the end of normal time in sight.
Sub Jamie Conn did brilliantly to tee up Frye who sent an effort wide before Moore shot against the legs of Law as 'Nock battered on the door looking for the vital breakthrough.
And just as it looked like the clock had beaten both sides, Cumnock forced their way over the line when Frye forced home a Willet cross which had been flicked on by Moore to break the hearts of Rutherglen and spark the mother of all parties in Cumnock this weekend.
