Luton Town cruelly paid the price for missed chances as a late goal from the experienced Jordan Rhodes saw the Hatters' dreams of reaching the Premier League ended as Huddersfield reached the play-off final at Wembley later this month.
With the Hatters having the better of the opportunities throughout the contest, particularly first half, they just couldn't take them and were hit with a sucker punch just nine minutes from time, Rhodes sliding in at the back post to convert Sorba Thomas's free kick for what proved to be the winner.
Earlier, Town had made two changes for the game, with Danny Hylton and Robert Snodgrass replacing the injured Henri Lansbury and Cameron Jerome, who dropped to the bench.
There he was joined by top scorer Elijah Adebayo, who had recovered sufficiently from his hamstring injury to take his place among the substitutes.
The hosts also made two alterations, Pipa and Levi Colwill in for Ollie Turton and Naby Sarr, who scored against the Hatters in the league fixture here last month.
After having to weather some early pressure, the Hatters had the best opening on seven minutes, Snodgrass slipping Harry Cornick through on the left, but on his weaker foot, he couldn't get a decent connection, scuffing well wide.
It was to unfortunately prove a theme, when a quick free kick saw Cornick escape on the right, but this time the Terriers defence were back in time to block.
While just 11 minutes, the Town forward had his best opportunity, and one he simply had to score, all coming from Hylton nicking the ball off Duane Homes.
Allan Campbell picked out the run of Kal Naismith on the left and his pinpoint cross was perfect for the unmarked attacker to tap home, but unfortunately for him, he sidefooted straight at Lee Nicholls, who didn't know much about the save, when either side and the visitors were in front.
Still Luton remained on the front foot, a glorious crossfield pass by Naismith picking out James Bree, with the ball fed back to Snodgrass. He went for goal from 20 yards, with Nicholls unconvincingly parrying his shot, the ball hitting Amari'i Bell and going wide.
With 18 gone, the hosts, who played plenty of neat football up until the penalty area, created a first chance of note, top scorer Danny Ward stooping to direct his header from Danel Sinani's cross over the top.
Still the Hatters remained the team that looked the more likely though, a clever throw-in releasing Bree in the area and his cross-shot was palmed aside by Nicholls, the ensuring corner missed by Hylton and flicking Campbell, dropping inches wide.
Clark was next to go close on 37minutes, taking his effort from outside the box early as Nicholls comfortably collected, before the Terriers then had their best opening, a wonderful mazy run from Harry Toffolo seeing him beat a host of visiting defenders, to face up Ingram, the Luton stopper making a big one-handed save.
The hosts were hit by an injury five minutes before the break, top scorer Ward forced off and the Rhodes replacing him.
Luton still couldn't get the goal their first half display totally deserved, Bree sending one in from 20 yards, but yet again, it was straight at Nicholls who had no trouble in gathering.
The final action of the first period saw Sinani curl a free kick wastefully wide as a goal for the hosts at that juncture would have been bitterly undeserved.
As expected, the Terriers, no doubt having been given a rocket by manager Carlos Corbwean started at a lively pace, winning an early corner, Bell getting in the way of one header, the next nodded over by Tom Lees.
Now looking a difference side, Sinani had a pop from range, Ingram saving low down as the home fans responded to what they were seeing, Town having to stand firm in the face of some severe pressure.
Jones' men did just that though and got a foothold themselves once more, a good move on the right seeing Campbell stretch to cross and Bell's header, which looked to have come off a defender, inches wide of the target.
With Clark and Naismith booked in quick succession, the latter gave away a free kick that the Terriers thought they had broken the deadlock from, Tom Lees guiding his header into the bottom corner, but thankfully for Luton, the whistle had already gone for a foul on Bradley, and the goal was chalked off.
And end to end encounter saw Cornick's curler bounce off the head of a covering defender and go wide, while as he had done in the first leg, Naismith was almost the provider again, delivering another terrific set-piece that Jerome, now on for Hylton, directed the wrong side of the post.
Cornick had yet another opening on 72 minutes, set free by Jerome, as his shot was parried by Nicholls, Bree unable to turn the rebound in and Clark's fizzing follow up blocked.
Huddersfield transferred play up the other end and Sorba Thomas low shot was saved by Ingram, who then got across his line to prevent a follow up cross headed in.
However, the keeper spilt the ball in the process and clearly fouled the lurking Toffolo, extremely unlucky not to give away a penalty, referee Peter Bankes somehow waving the appeals away, much to the chagrin of the majority of the John Smith's Stadium.
Ingram was then more positive with his next action, off his line to punch clear, but with Luton initially looked to run the ball away from danger, Bree then clipped his man for a free kick that was to prove crucial.
Thomas took it and and Rhodes got clear at the back post from the attentions of Bell to slide in at the far post and break Town hearts.
In the closing stages, Carlos Mendes Gomes came on for a late cameo, as Pipa's blast was over the top, while a clearly unfit Adebayo had the final seconds, but the Terriers saw out the final moments, with the full time whistle sparking a pitch invasion as the Hatters were beaten.
Terriers: Lee Nicholls, Harry Toffolo, Jonathan Hogg ©, Lewis O'Brien, Duane Holmes (Naby Sarr 85), Pipa, Danel Sinani (Sorba Thomas 61), Danny Ward (Jordan Rhodes 41), Levi Colwill, Tom Lees, Jon Russell.
Subs not used: Tino Anjorin, Jamal Blackman, Carel Eiting, Naby Sarr, Josh Ruffels.
Hatters: Matt Ingram, James Bree, Reece Burke (Carlos Mendes Gomes 86), Sonny Bradley ©, Kal Nasmith, Amari'i Bell, Robert Snodgrass, Allan Campbell, Jordan Clark, Danny Hylton (Cameron Jerome 65), Harry Cornick (Elijah Adebayo 89).
Subs not used: Harry Isted, Dan Potts, Tom Lockyer, Peter Kioso.
Bookings: Clark 59, Naismith 65, Jerome 81.
Referee: Peter Bankes.