Andrew Waterworth scored a hat-trick as Linfield beat Coleraine 3-0 at Windsor Park to complete the Premiership and Irish Cup double.
The striker's near-post finish from Paul Smyth's low delivery put David Healy's men into a 29th-minute lead.
Waterworth was in the ideal position four minutes later to snap up a rebound from about eight yards after keeper Chris Johns had saved from Aaron Burns.
Smyth set up Waterworth again to complete the victory near the end.
The Irish Cup triumph was the climax of former Northern Ireland striker Healy's first full season as Linfield manager, which also included a County Antrim Shield success.
Last week, 31-year-old Waterworth scored a hat-trick as Linfield beat Cliftonville to clinch the Irish Premiership title.
Linfield, the most successful club in Northern Ireland, have now won the Irish Cup on a record 43 occasions and they have won eight of their past nine finals.
Coleraine, who last lifted the trophy in 2003, will be hugely disappointed with their performance on the showpiece occasion.
Managed by former Linfield midfielder Oran Kearney, the Bannsiders took too long to get into any sort of rhythm and, by the time they did, they were two down and staring defeat in the face.
More Windsor memories for Healy
There were some who questioned whether Northern Ireland's record goal scorer Healy had the attributes to become a successful manager when he succeeded Warren Feeney in October 2015.
Was he too quiet? Did he know enough about the Irish League scene?
The 37-year-old will feel he has more than answered those questions.
Last spring, after six months in charge, Linfield were runners-up in league and cup, now they've gone one better.
Healy has had magical moments at this Windsor Park ground in the past - Northern Ireland's winner against England in a World Cup qualifier in 2005 and the brilliant hat-trick against Spain the following year.
Judging by his celebrations, the man who scored 36 goals for his country values this season's achievements just as highly.
Coleraine's costly slow start
Coleraine fans travelled in their thousands hoping to see the club celebrate serious silverware for the first time in 14 years.
But they were to be bitterly disappointed as Kearney's young side struggled to make a mark on the big day.
Six of their starting team were 21 or under and only striker Eoin Bradley had played in a previous Irish Cup final.
That inexperience showed and Coleraine were unable to play with the freedom and flair which had seen them go on a great run which earned them a third-place finish in the Premiership and a cherished appearance in the cup final.
They were better in the second half, and had some half chances, but could not produce a telling response.
What they said
Linfield manager David Healy: "This final was all about redeeming ourselves after we underperformed this time last year.
"I thought we were by far the better side and deserved winners today, it was a good performance from us. I'm so privileged to be manager of this club and work with the calibre of players that I have."
Linfield's hat-trick hero Andrew Waterworth: "It's been a long five years for Linfield but I'm delighted for everyone associated with the club. Hopefully we can kick on from here.
"I feel on top of the world. Three trophies in one season, I've dreamt of this for a long time."
Coleraine manager Oran Kearney: "I thought we started well but we struggled to keep possession of the ball after that.
"Congratulations to Linfield though. We couldn't cope with them for a 20-minute spell in the first half.
"A goal in the second half could have dragged us back into it but it wasn't to be."