Peterborough manager Darren Ferguson said his team 'did him proud' as they booked their place in the League One play-off final.
Posh beat MK Dons 2-0 in their semi-final second leg to overturn a 3-2 deficit from the away leg and win 4-3 on aggregate.
Captain Grant McCann gave the hosts an 11th minute lead at London Road with a clever free-kick and Daniel Powell almost equalised for Dons as he struck the underside of the crossbar in the first half.
But top-scorer Craig Mackail-Smith put Posh ahead on aggregate in the 54th minute and Ferguson's men should have made their victory more emphatic late on.
They will now face Huddersfield at Old Trafford a week on Sunday, 29th May, hoping to secure a third promotion in four years.
"It was fantastic," Ferguson told Sky Sports 1. "I know we've had two promotions before but tonight is a special night.
"The players have done me proud. To a man they were magnificent. It was a great performance.
"I just thought we had to keep the ball better (than the first leg), and the main thing was pressing. We worked on that all week.
Spot on tactics
"We had to press better when they had the ball and I thought tonight they did it perfectly. Tactically, they got it spot on.
"When you miss that many chances you're never sure, but we got there in the end. It's a fantastic night."
Mackail-Smith pounced from close range to claim his 34th goal of a season which has seen him handed his international debut with Scotland and the 27-year-old, who is set to leave the club this summer, also struck a post late on.
"I don't know where he gets that energy," Ferguson added. "I'd like to drink what he's drinking.
"He's a great lad and he deserves everything he's got. To score the winner tonight, I'm really pleased for him, but it'd be wrong of me to just say Craig, it's down to the whole team."