Waterford's dreams of a first All-Ireland SHC final appearance since 1963 were dashed in the Croke Park rain as 'super sub' Cathal Naughton rescued Cork in a tense 1-16 to 1-15 victory.
The Newtownshandrum youngster came off the bench to score a vital 1-01 as the champions maintained their treble aspirations in front of 61,753 spectators.
Cork were two points ahead of the Deise on seven occasions in the first half but two late John Mullane points made it 0-08 apiece by the break.
Top scorer Eoin Kelly (1-06) rattled in a 36th-minute goal to help Waterford go four points clear, but Naughton's 59th-minute strike gave the Rebels enough of a cushion to book their spot in the 3 September decider.
This meeting of the Munster minds really came to a head in the second half, sparked by McGrath's early goal.
Waterford were over reliant on Kelly, and although John Mullane cracked over four points from play, the underdogs were caught out in the finish as Dan Shanahan and substitute Paul Flynn, amongst others, made little or no scoring contribution.
Bar Mullane's efforts, only Shanahan, Seamus Prendergast and Eoin McGrath scored from play, while the winners only needed four points from frees – all from Joe Deane.
However, in the end, just as they were forced to do in their quarter-final win over Limerick, John Allen's champions were left scrambling for points as they staved off an injury-time fight back.
Twice Mullane had replied to Deane frees to keep the gap to the minimum but time ran out on the luckless Deise, who were losing to Cork for the seventh time in ten championship clashes.
Would it be a case of unlucky 13 for Allen's charges? The Leesiders came into today's tie on a 12-game unbeaten run in the Championship, stretching back to their 2004 Munster final defeat by Waterford.
Deane gave his side the lead with a free inside 90 seconds and Timmy McCarthy made it 0-02 to 0-00 soon after, flashing over from 35 metres out.
Cork 'keeper Donal Óg Cusack, who was once again in imperious form, showed superb instinct to clear a '65' from Ken McGrath that dropped short, and while Kelly slung over his first free, midfielder Tom Kenny struck over at the other end for a 0-03 to 0-01 Cork lead.
Kelly angled over three of Waterford's next four scores from frees, with McGrath also off the mark, but they were all preceded by points from play from Cork as their attack clicked into gear.
The ageless Brian Corcoran looked particularly impressive when he cut across to either wing to fire over two excellent points, with the second arriving after some sterling defensive work from Sean Óg Ó hAilpín.
With both teams coping admirably on a slippery top surface, Neil Ronan skated through to put Cork 0-06 to 0-04 ahead coming up to the half hour. Kelly's fourth free was followed by a second point from McCarthy, who took a Ben O'Connor hand pass before slamming it between the uprights.
Waterford's first point from play finally came on 33 minutes when Ó hAilpín miscued a sideline ball back to Cusack and Shanahan lapped it up to score. And Mullane's brace, rubbing out a Ronan point, gave the Deise, who had been dominated for long spells, the necessary spark for their second half assault.
The second period was barely 30 seconds old when Cusack was plucking the sliotar out of his net. A swashbuckling attack saw Shanahan's deft touch send Eoin McGrath into space and although Cusack reacted smartly to save twice from the corner forward, the ball squirted invitingly free to Kelly, on the right edge of the square, and he made no mistake off the ground.
A Prendergast point sent Justin McCarthy's side into a 1-09 to 0-08 lead, and Cork were in serious danger of being toppled. Yet a couple of crucial points – from the in-form Ronan and Timmy McCarthy – got the champions back within two.
Ken McGrath then registered a mammoth free before Jerry O'Connor showed a great turn of pace to point and Kelly and Deane swapped further frees. The deficit was still two when teenager Naughton came on in place of Ronan.
By that stage Waterford had also brought on their regular captain Paul Flynn, who is set to go in for a hernia operation soon, but it was the pacy Naughton who made an immediate impact, swinging over an inspirational point from the right flank.
Then Cork really stepped up to the plate. Deane, helped by a Corcoran flick, gobbled up possession 30 metres out from goal and slung a hand pass in for the unmarked Naughton who rasped home his first championship goal. The Rebels were now two points to the good.
Naughton took his goal with all the experience of a veteran forward as he shortened his grip before sending his strike clean past Clinton Hennessy on his right side.
A Jerry O'Connor point strengthened Cork's grip on the game as they went 1-14 to 1-11 clear with eight minutes remaining. With star performers in Cusack, Ronan Curran and the O'Connor twins, Cork had a bit of breathing space.
Waterford still made them sweat at the finish as two frees from the Deane were cancelled out by Kelly (free), Eoin McGrath and Mullane (0-02). Prendergast twice set up Mullane for rip-roaring scores on 67 and 70 minutes.
Two timely interceptions from Curran paved the way for Ben O'Connor to have a shot at the posts but his effort tailed wide. Ironically Ken McGrath, who had given away a silly free for Deane's last point, had a chance to draw the game in deepest injury-time with a free of his own.
The Mount Sion man was 65 metres out, he let fly and frustratingly his effort bounced back off the post. An almighty scrap for possession ensued with Cork emerging with the ball, and the spoils as they marched triumphantly into their fourth successive final.
Cork: D Óg Cusack; B Murphy, D O'Sullivan, P Mulcahy (capt); J Gardiner, R Curran, S Óg Ó hAilpín; T Kenny (0-01), J O'Connor (0-02); T McCarthy (0-03), N McCarthy, N Ronan (0-03); B O'Connor, B Corcoran (0-02), J Deane (0-04 (4f)).
Subs used: C Naughton (1-01) for Ronan (57 mins), K Murphy (Sarsfields) for N McCarthy (68).
Waterford: C Hennessy; D Prendergast, T Feeney, E Murphy; T Browne, K McGrath (capt) (0-02 (2f)), J Murray; E Kelly (1-06 (6f)), B Phelan; D Shanahan (0-01), S Prendergast (0-01), J Kennedy; J Mullane (0-04), M Walsh, E McGrath (0-01).
Subs used: P Flynn for Kennedy (46 mins), S O'Sullivan for Phelan (56).
Referee: Brian Gavin (Offaly)