The Italian centre-back, who is expected to leave Rangers for English Premiership side Blackburn Rovers this summer, got his head to a Neil McCann free-kick in the 66th minute to break the resistance of a spirited Dundee side.

The win extends a remarkable run for Rangers under manager Alex McLeish, who has now won every domestic title available to him since taking over from Dick Advocaat midway through last season.

At that stage, Celtic were too far ahead for Rangers to make an impression in the league.

But both Cups were brought back to Ibrox and this season had already seen McLeish's men reclaim the ascendancy in the Scottish game by beating Celtic in the League Cup final then pipping their old rivals at the post in the league race.

"It is a wonderful feeling," the Rangers boss told Sky Sports.

McLeish admitted it had been a relief to hear the final whistle as the effects of a long hard season took their toll.

"We were walking on empty at the end," he said. "We needed to score in the second half because extra time would have killed us.

"We had one of two players with injuries and cramp but we've dug deep and I'm proud of the players."

Amoruso, a survivor of the Rangers squad that lifted the club's last treble in 1998, was overcome with emotion after the final whistle.

"I already won the treble five years ago but this one is so special because it has been so difficult," he said.

The Italian said he would take a two-week holiday before making a decision about his future.

"I don't know if I will go or if I stay but if I do go it was the best way for me to say goodbye to the Rangers fans.

"My six years in Scotland have been fantastic. Now I just want to enjoy this moment with my teammates and the fantastic Rangers fans."

Dundee, who have the consolation of knowing their Cup run has earned them a place in next season's UEFA Cup, were by no means overawed by their all-conquering opponents.

They did enough in the first hour of the match to suggest they were capable of defying the odds and lifting the Scottish Cup for the first time since 1910.

But they were made to pay a heavy price after conceding a free-kick close to the touchline on the left of their own box.

Winger Neil McCann curled an inswinging cross in to the edge of the six-yard box. The charging Amoruso got there a split second ahead of Dundee goalkeeper Julian Speroni and the finest of touches was enough to carry the ball into the net.

Amoruso celebrated with a relish that suggested he could well be on his way south and was determined to enjoy his farewell to the Rangers fans.

But he nearly blotted his copybook a quarter of an hour from the end when he badly misjudged a long ball into the Rangers box, allowing it to fly over his head.

Behind him, Nacho Novo had got inside Kevin Muscat but the Dundee substitute failed to connect cleanly and the ball spun away to safety.

Despite that setback, Novo continued to pose a threat to the Rangers defence. With nine minutes left his neat layoff left Steven Milne with a free shot from barely ten yards out but his strike partner failed to get any power into his shot and Stefan Klos was able to gather comfortably.

Both sides hit the woodwork in the first half with Dundee signalling their determination not to be overawed by threatening as early as the fourth minute.

Skipper Barry Smith unleashed a fierce drive which looked to have beaten Klos but crashed off the German goalkeeper's left-hand post.

Rangers hit back in the 15th minute when Dutch striker Michael Mols rose above the Dundee defence to head Neil McCann's free-kick against the crossbar.

Dundee goalkeeper Julian Speroni had been beaten by the power of Mols' header but he recovered well to punch the rebound away from the advancing Craig Moore.

Ronald de Boer was having an unusually quiet match in midfield for Rangers but the Dutchman did produce one flash of his extensive array of skills in the 25th minute.

After turning Zurab Khizanishvili superbly, he waltzed past Lee Mair to the edge of the box but his low shot, which Speroni touched wide, was disappointing by his high standards.