After another tense dual, Huddersfield prevailed as substitutes linked up to break the deadlock. It was Jordan Rhodes' 200th career goal and his 119th in the Championship was debatably his most important yet.
Sorba Thomas provided a pinpoint ball to the back post for his 15th assist of the season. In the final knockings, the Terriers saw off a determined Luton and now they look forward to either Nottingham Forest or Sheffield United.
Chelsea loanee Levi Colwill came in for his first start in three games. His presence was at the expense of Naby Sarr, who dropped to the bench. Josh Ruffels returned to the bench, along with Sorba Thomas.
Luton Town: Ingram; Bree, Burke, Bradley (C), Bell; Campbell, Snodgrass, Clark; Hylton, Cornick.
Substitutes: Isted, Potts, Adebayo, Mendes Gomes, Lockyer, Kioso, Jerome.
Story of the match
The Hatters had the first of several good opportunities in the first half just 11 minutes in. Kal Naismith found Harry Cornick with a low driven cross. Although right in front of goal, the forward couldn't put it either side of Lee Nicholls who stood up strong to block.
Just five minutes later, Robert Snodgrass tested Nicholls once more with a curling strike outside the box. The former MK Dons and Wigan man perhaps made a meal out of a relatively routine looking stop, parrying the ball. Luckily for him, Amari'i Bell couldn't make the most of the rebound.
Luton employed a tenacious press and Huddersfield did well when they could break, often driven by Lewis O'Brien and Danel Sinani. The Terriers would have the next chance - on 19' Sinani floated in a tempting ball from the left but Danny Ward's glancing header was high of the target.
Following another strong period for Luton, Huddersfield broke away again. This time 37 minutes in, in form Harry Toffolo was making his presence known. The left back took on a marauding run into the box and forced a fine stop from Matt Ingram, his strong left hand keeping it goalless.
Just after, Danny Ward slipped of his own volition in the box and looked to injure himself. It was a hit for Huddersfield when he was unable to run off the pain, being replaced by Jordan Rhodes on the 40 minute mark.
There were a number of half chances as the hosts came out strong. Danel Sinani's shot from range straight at Ingram offered the visitors the opportunity to get their breath back.
After this, Luton looked to retrieve their previous initiative. Amari'i Bell went close following a great Allan Campbell cross on the right.
On 64 minutes, Huddersfield would have the ball in the net. Yet despite the celebrations, the ref had blown up early. Sonny Bradley clashed with Levi Colwill on the edge of the box and was perhaps lucky to get the decision as Tom Lees headed home.
Up the other end, hometown boy Cameron Jerome came close on 70'. His diving header following a Snodgrass free kick just bounced wide of the left post. It would be another good chance just minutes later as Harry Cornick couldn't beat Lee Nicholls who covered his right post well.
After this, the Terriers turned up the pressure. On 75 minutes, Matt Ingram was forced to make two great saves. The first was from a low effort from the edge of the box out of the bottom right corner. Then, Ingram was scrambling across his goal line to palm a header out. In this, the loanee was wrapped up in controversy as Harry Toffolo threw himself at the keeper and the ball. Much to he, and the fan's uproar, referee Peter Bankes waved play on instead of pointing to the spot.
Huddersfield's pressure would finally force a breakthrough eight minutes from time. Influential substitute Sorba Thomas delivered a beautiful ball from the left sided free kick and Jordan Rhodes was there at the back post to slide it in artfully.
On 90', Nathan Jones went for one last flip of the coin bringing Elijah Adebayo on. Alas, in the signalled additional four minutes, Huddersfield showed expert game control to book their place in the play-off final. Now, either Sheffield United or Nottingham Forest await as Premier League football beckons.