Not only did they revive their hopes of reaching the play-offs, they also ended the Welsh side’s hopes of finishing in an automatic promotion place.
Neil Mellor’s 11th goal of the season started the rout, guiding in Jon Parkin’s flick and he added his 12th before half-time.
Paul McKenna struck from the edge of the area after a headed clearance from a corner and the No.33’s heavy deflection saw it past the keeper.
Cardiff fell apart in the second half against a rampant North End.
But it was a vital moment on the stroke of half-time that was key to the result and ultimately the one-goal difference at the end of the season that led PNE to pip Dave Jones’ side to a place in the top six.
After Billy Jones had fouled Joe Ledley, Ross McCormack, normally a dead eye from the spot, saw his 45th-minute penalty brilliantly saved by Andrew Lonergan, in front of the Alan Kelly Town End to keep it 2-0 at half-time.
It was the first time that the Scot has missed from 12 yards all campaign.
And then, after the interval, Jon Parkin made it 3-0.
Released through on goal not far inside the City half to keep clear of the retreating defence and slot under Stuart Taylor.
An own goal by Mark Kennedy made it four, the defender dispatching his header into the corner of the net from Mellor’s cross – a finish a forward would have been proud of.
There was still time for two more, Chris Brown netting the fifth.
Neat work from Chris Sedgwick, intentionally deployed on the left wing to confuse the Cardiff defence, picked out Brown who was never to miss his header from the centre of the box at close range.
On-loan midfielder Lee Williamson finished off the scoring, PNE playing with confidence as they knocked the ball about. The Lilywhites cut Cardiff open with quick passes and the Jamaica international finished well from just outside the area.
After the game, manager Alan Irvine was pleased, but knew his side still needed help in order to achieve their top six ambition: “The play-offs are still not in our hands,” he said. “We are waiting to see what happens.
“We have kept ourselves in with a chance. Before the game the gist of my talk to them was that it’s now or never, that they had to go out and do the job.
“But I certainly didn’t see this coming. I don’t think anyone would have imagined that happening for a moment.
“We went 2-0 up and I felt that was probably a bit harsh on Cardiff. They were probably the better team in the first half and we got our goals pretty much against the run of play.
“The penalty save by Andy Lonergan I felt was a key moment.
“Also I had made a decision to put our two wide players on opposite wings, to do something a little bit unexpected perhaps that Cardiff would not be prepared for.
“It worked, but on another day it might not have.
Cardiff manager Dave Jones was equally surprised with the result, he said: “I didn’t see that coming, we just didn’t turn up and failed to do what we have been doing all season. Full credit to Preston but they didn’t have to work too hard.”