Steve Morison and Paul Robinson bagged the goals as magnificent Millwall booked a League One Play-Off final date with Swindon Town on Saturday 29th May.
Victory against Huddersfield Town in Tuesday night's semi-final second leg was no more than Kenny Jackett's lionhearts deserved after they served up a rip-roaring display.
Striker Morison set the victory wheels in motion with a clinical finish on 22 minutes before captain fantastic Robinson sealed success with a killer second goal seven minutes from time.
On an unforgettable night at The Den boss Jackett welcomed back Danny Schofield to the starting line-up in place of Marc Laird, the only change to the team that secured a 0-0 draw at the Galpharm Stadium on Saturday.
Schofield took his place on the right flank with Scott Barron filling the left wing berth.
Huddersfield boss Lee Clark made one change to his side, replacing injured defender Tom Clarke with Robbie Williams.
Millwall were roared on by a vocal and passionate crowd of 15,463, who were in full voice from long before skipper Robinson led the team out.
And to a man, the players responded magnificently.
The Lions started at an incredible tempo, pressuring the Town defence and taking every opportunity to deliver crosses into the box.
Robinson narrowly failed to connect with a ball in from Neil Harris following a smart Barron free-kick whilst Alex Smithies did well to hold Morison's firm header on seven minutes.
Jimmy Abdou's 15th-minute shot was clawed away for a corner by keeper Smithies as The Lions continued to press forward, but without finding a way through a solid Town rearguard.
Having weathered the early Millwall storm, Huddersfield started to settle into their stride and looked lively on the break.
David Forde had to be alert to save an attempted clearance from Abdou that flew off Anthony Pikington's backside and the Lions keeper later tipped a Lee Novak effort around the post.
But The Lions responded and when Schofield showed great skill and vision to create space before crossing from the right, Smithies parried and there was Morison, showing his predatory instincts, to slam home the opener from close range for his 23rd goal of the season.
Town hit back, forcing two corners in as many minutes, the first of which came when Forde athletically tipped Pilkington's goalbound cross-shot over his crossbar.
The visitors brief flurry of pressure was comfortably dealt with though, and with Abdou and central midfield partner Liam Trotter taking control, it was Millwall who regained the upper hand once again.
Jack Smith was a whisker away from adding a second goal on 36 minutes, firing wide from Morison's cross after sprinting virtually the length of the pitch.
Morison then headed narrowly over from a corner as The Lions pushed for a second before the break.
There was little sign of a Town equaliser in the opening period after the restart and boss Lee Clark replaced Jordan Rhodes with Theo Robinson nine minutes later.
Both teams looked a tad nervy as the enormity of the occasion seemed to effect them and for around 10 minutes passes went astray as the anxiety levels off the field rose too.
Barron nearly settled those nerves on 67 minutes with a superb solo run into the area before striking the underside of the crossbar with a thunderous rising shot.
Harris then provided a deep cross that Abdou headed over as The Lions turned the screw.
That second, crucial goal finally arrived eight minutes from time when Barron whipped over Millwall's first corner of the second half and up popped Robinson to powerfully head into the roof of the net to send the home fans wild.
Substitute Gary Alexander might have added a third with his first two touches when he was picked out perfectly by another Barron corner, but his low angled strike was saved by Smithies.
Huddersfield tried without success to make any headway as Millwall remained resolute to keep a second successive clean sheet on their way to a second successive Wembley appearance in the Play-Off final.
Millwall: Forde, Smith, Craig, Abdou, Robinson, Ward, Barron, Trotter, Harris (Alexander, 88mins) , Morison, Schofield. Subs not used: Sullivan, Laird, Frampton, Fuseini, Batt, Obika.
Booking: Craig (73mins)
Scorers: Morison (22mins), Robinson (83mins)
Huddersfield Town: Smithies, Peltier, P. Clarke, Trotman (N.Clarke, 83mins), Williams, Roberts, Kay, Drinkwater, Pilkington (Eccleston, 75mins), Rhodes (Robinson, 53mins), Novak. Subs not used: Eastwood, Collins, Goodwin, Simpson.
Bookings: Pilkington (11mins), Kay (32mins), Peltier (89mins)
Ref: Tony Bates
Att: 15,463 (away 1,286)