The result also ended the Crues' chances of making it a Cup treble of their own this season, as they have already won the League Cup and still have the Setanta Cup final to come.
Linfield went 2-0 up in the first half of the match at Windsor Park with two strikes from Man of the Match Mark McAllister.
Colin Coates pulled one back for Crusaders when he scored from a free kick on 57 minutes, but Michael Carvill replied for the Premiership champions four minutes later from another set piece.
Then with eight minutes remaining Jamie Mulgrew wrapped it up when he made it 4-1 from a Chris Casement pass.
"It might appear a comfortable scoreline but it was far from that - it was a very difficult game, a very tough game," Linfield manager David Jeffrey told UTV.
"First half we knew what to expect, Crusaders were going to be quick out of the blocks, but I thought we coped with that very well."
Six doubles in seven years is fantastic. You win a game of football, you win a trophy - you win a trophy then you make a record
The Blues made a bright start to the match at Windsor Park and William Murphy came close on 14 minutes, but his header was deflected away to safety by the north Belfast men.
Linfield came into the tie more and on 17 minutes they broke dangerously, however Michael Carvill saw his strike saved.
On 23 minutes the Crues had a dangerous looking set piece chance but Gareth McKeown's shot sailed over the bar.
A crucial couple of moments came just after the midway point of the half when, firstly Crusaders had a promising opening which led to a corner.
Adamson came close for the Seaview side with a header but it went to safety.
And then just two minutes later the champions scored.
A neat move developed with Peter Thompson involved in the build-up, and Mark McAllister applied the finish to make it 1-0.
Linfield continued to press and on 31 minutes Lowry came close, but his shot was charged down by the Crusaders defence.
Gareth McKeown saw the space open promisingly for him soon afterwards, however his shot was deflected wide.
However five minutes from the interval, came another critical development, Linfield doubling their lead when McAllister followed up to net after Crusaders goalkeeper Sean O'Neill could only parry the initial shot out.
"Over the moon - I've scored two goals and the team has gone on and won the game comfortably in the end," McAllister told UTV.
"It's my third double since I came here and I'm hoping for more next year."
Crusaders had it all to do in the second period, but they came out fired up and determined to make a game of it with skipper Colin Coates firing over the bar after a goalmouth melee straight after the re-start.
Linfield could have made it three, but Robert Garrett was left with his head in his hands after his volley veered over the bar.
On 55 minutes though the stroke of luck the Crues needed arrived as Coates lined up a free kick from just outside the area.
His effort took a deflection, beyond the reach of Alan Blayney and as the ball nestled in the net, Crusaders had renewed hope.
Manager Stephen Baxter however will have been crestfallen as having got a foothold back in the tie, Linfield re-established the two-goal buffer just four minutes later.
And again it came from a free-kick, Michael Carvill stepping up to arc the ball superbly into the net to make it 3-1.
It was a body blow for the Crues and their hopes of adding the Irish Cup to the League Cup they secured earlier in the campaign.
Jordan Owens thought he had cut the arrears, but was denied by a smothering save from Blayney.
With time running out for the Seaview side, they attempted to apply late pressure on Jeffrey's side but Adamson's close-range header from a dropping ball went wide from six yards out.
Linfield scored their fourth and crowning goal, seven minutes from the end.
Good build-up play down the right saw the ball eventually cut-back to Jamie Mulgrew who shot low into the goalkeeper's left-hand corner to complete the win for Linfield and their 42nd Irish Cup win in all and a second consecutive win over Crusaders in the blue ribbon event.
Crues manager Stephen Baxter was left dejected by the result, but insisted the task in hand now is to lift the squad ahead of next week's Setanta Cup Final.
"We didn't do enough on the day," he lamented. "We had to chase the game (at 2-0).
"Linfield were clinical and we weren't. We have to re-group and re-focus for another massive game next week."
JJB Sports Irish Cup Final result:
Linfield 4-1 Crusaders
Linfield: Mark McAllister 28 + 41, Carville 60, Mulgrew 83.
Crusaders: Coates 58.
Linfield: Blayney, Curran, Murphy, Watson, Ervin, Carvill, Garrett (Casement 71), Mulgrew (BJ Burns 89), Lowry, McAllister (Fordyce 92), Thompson.
Crusaders: O'Neill, McKeown (Leeman 45), McBride, Magowan, Coates, Dallas, Morrow, Adamson, Rainey, Caddell, Dallas, McMaster (Owens 45).