A late rally by the Castleknock side reduced the deficit to 11 points, but in truth the winning margin could have been twice that, and there wouldn't have been too many complaints.
The Marino side began like they meant business, and for the majority of the first half Castleknock were like a rabbit caught in the headlights.
By half-time the score was 3-10 to 1-1, and by the 52nd minute that had increased to 4-18 to 3-2.
Though the dogged Castleknock side did manage a confidence restoring 1-5 in the final eight minutes, you could not fail to admire the comprehensive nature of the Ardscoil victory.
From the throw-in, Ardscoil were first to every ball and won almost every individual battle on the field. It was, then, hardly surprising that collectively the Ardscoil team proved so dominant.
Every 50-50 ball ended up in the hands of a white shirt, and from a point of dominance in midfield -- where Gavin Byrne was a relentless force in driving his side forward -- Ardscoil were able to unleash their potent attacking game.
It also helped the Ardscoil cause that they happened to have the most dynamic and productive player in the game in the shape of centre-forward Cormac Costello.
The Marino youngster appeared to have some sort of magnetic pull over the ball and his shooting certainly was not affected by the frost that stubbornly refused to shift from the Ballymun Kickhams venue.
Costello's cultured boots were responsible for 3-8 -- well over half of his side's tally -- in a game that he dominated from start to finish.
While there was certainly a sprinkling of fortune in some of the Ardscoil goals, there can be no denying the power of this young side.
With the spine of the team so strong and skilful, it will certainly take a tough side to beat them in the final.
Shane Ruane was a rock at full-back, as was captain Jack Collins on the 40, while Conor Mullins and Sean O'Keefe patrolled the flanks and snuffed out plenty of Castleknock challenges.
However, it was going forward that Rís really shone. And with Byrne and Costello the instigators, the likes of Greg Murphy and Sean Heaney were able to buzz effectively around the totem pole full-forward figure of Brian Purcell.
The game began with a taste of what was to come, with Byrne making a clean catch in midfield before driving through the heart of the Castleknock defence to put over the first score of the game after two minutes.
Heaney and Murphy soon added their name to the scoresheet before a hat-trick of beautifully-struck points by Costello sent Rís six clear after just 10 minutes.
However, against the run of play, Castleknock's Jack Collins beat a static defence to fist in Ian McSherry's ball and give the underdogs an early lifeline.
That merely sparked Rís into gear, though, and a jinking run at full throttle ended with Costello rifling the ball into the net, as if to emphasise a point.
When Heaney's scuffed shot crept under the bar for a second goal on 25 minutes, you sensed it was not going to be Castleknock's day.
And so it proved as, just before the break, Costello's sideline ball arced untouched and into the net to end a one-sided half.
Castleknock needed something, but again the breaks went against them early in the new half when Heaney's shot bounced off the bar and Costello was on hand to palm the ball over the line for a fourth goal.
It was the killer score, and Rís kept the scoreboard ticking over thereafter.
Castleknock, to their credit, never threw in the towel, and full-back John O'Hare was certainly steadfast in his defensive duties.
Dynamic midfielder Adam Noonan pulled a goal back when his booming shot snuck in under the bar.
And lightning quick corner-forward David Costello got his rewards for a tireless display when he fisted in a Noonan ball to the net.
A thunderous strike by substitute Conor Burn helped Castleknock end the game with their tails up, but, it is Ardscoil Rís who march on to the decider, and deservedly so.
SCORERS -- Ardscoil Rís: Cormac Costello (3-8), Sean Heaney (1-1), Gavin Byrne (0-4), Greg Murphy (0-3), Brian Purcell (0-1), Dylan Smith (0-1).
Castleknock CC: Adam Noonan and David Costello (1-1 each), Jack Mullins and Conor Burn (1-0 each), Mark Prunty (1f), Keelan McAnerin, Ian McSherry, Matthew Murphy and Brian O'Malley (01 each)
ARDSCOIL RÍS -- Robert Lenihan (Luke Carey) ; Martin Moore (Cian Pender), Shane Ruane, Conor Mullins; Sean O'Keefe, Jack Collins, Kevin O'Donohue (Padraig Smith); Tommy Byrne, Gavin Byrne; Conor Dolan, Cormac Costello, Sean Heaney; Greg Murphy (Dylan Smith), Brian Purcell, Conor Gray (Conor McNamara)
CASTLEKNOCK CC -- Timothy Moran; Sean O'Malley, John O'Hare, Eoin Connor; Shane Ryan (Ciaran Millmore), Jack Mullins (Conor Burn), Luke Lynam (Michael Boland); Adam Noonan, Tom Moroney; Matthew McEntee, Tom Quinn, Keelan McAnerin; David Costello (Ryan Early), Mark Prunty (Matthew Murphy), Brian O'Malley (Ian McSherry)
REFEREE -- Dave Feeney (Parnells)