Kilkenny and Offaly enjoyed a tense, end-to-end battle for the vast majority of this match at O'Connor Park, but in the end Richie Mulrooney's side prevailed, as their greater resources on the bench overpowered the home side in the closing stages.
Michael Brennan's tally of 1-1 off the bench was critical, while fellow substitute Jack Langton picked up countless breaks and Conor Martin also won some crucial possessions for the Cats. In contrast, Offaly manager Ger Coughlan didn't look to his bench until the 56th minute, by which time several of his key players were visibly exhausted.
The first half was very evenly contested and with Stephen Quirke in fine scoring from play and frees, Offaly had the narrowest of advantages at the break, 0-9 to 0-8.
They led by three on a couple of occasions, but some needless fouls allowed John Power to keep the scoreboard moving for Kilkenny, even though Offaly were marginally the better team in open play.
Kilkenny moved up a gear once the game restarted and three early points put them back on the front foot. However, Offaly roared back again, their comeback set in motion by a wonderful Aodhan Kealey point from the right wing.
Quirke rattled the net from a 20-metre free in the 39th minute to put the home side in front and the same player put Offaly three up with a quarter of an hour to go after great work from Thomas Geraghty earned a free on the right wing, leading many supporters to believe that an upset was on the cards.
However, Power, who also hit three 65s over the hour, continued to punish Offaly indiscretions to keep Kilkenny in touch. Their breakthrough came in the 50th minute when Brennan took a handpass from Shane Donnelly and produced a sublime finish from a tight angle to give them the lead once again.
Offaly had their chance to regain the initiative when Willie Phelan was deemed to have pulled across Quirke in the penalty area, but the corner-forward lifted the ball too far forward and his tame shot was saved by Aaron Duggan.
From then Kilkenny dominated and started to find space in every nook and cranny of the O'Connor Park pitch. Kevin Kelly hit a magnificent point to give Kilkenny that vital four-point lead with two minutes left and two final scores for Power closed out the result and sent Kilkenny through to a Leinster final meeting with Wexford at Wexford Park in a fortnight.
Scorers – Kilkenny: J Power 0-10 (6fs, 3, '65), K Kelly 0-4, M Brennan 1-1, C Buckley, R Reid, S Donnelly, G Aylward 0-1 each. Offaly: S Quirke 1-10 (1-6fs), T Geraghty 0-2, A Kealey 0-1.
Kilkenny – A Duggan; J Nolan, W Phelan, P Walsh; J Corcoran, L Harney, B Kennedy; C Buckley, O McGrath; R Reid, J Power, O Walsh; G Aylward, K Kelly, S Donnelly. Subs: J Langton for Nolan (26), M Brennan for Reid (38), C Martin for O Walsh (49)
Offaly – C Clancy; N Wynne, D Kelliher, M Cleary; S Gardiner, P Camon, D King; S Cleary, T Carroll; S Dolan, A Kealey, P Geraghty; S Quirke, T Geraghty, A Hynes. Sub: J Sampson for Kealey (56)
Ref – J Heffernan (Wexford)