Adam Collin was the hero as he saved two spot-kicks to send Rotherham to back-to-back promotions as they triumphed over Leyton Orient 4-3 on penalties in an enthralling Sky Bet League One play-off final.
Collin kept out efforts from Mathieu Baudry and Chris Dagnall after it had finished 2-2 following 120 minutes to earn a return to the Championship after 10 years away.
It looked like Orient, who led the League One table for 22 weeks of the season, would end their 32-year absence from the second tier as Moses Odubajo and Dean Cox scored in five first-half minutes to put them firmly in control.
But the Millers hit back after the break with two goals from Alex Revell, against his former club, sent the game to extra time before Collin's heroics won it for Steve Evans' men, who came up from League Two last season.
It was harsh on Russell Slade's Orient as they played their part in an absorbing game and had a superb campaign, winning their opening eight matches.
An end-to-end contest was always on the cards as both sides scored freely during the regular season, with the Millers bagging 86 times and Orient 85, but a dour opening half hour did not follow the script.
However, the game burst into life with the first real moment of quality in the 34th minute and it was the highly-rated Odubajo that produced it to break the deadlock.
The Millers failed to clear a free-kick and the ball fell to the 23-year-old 20 yards out. He controlled it and let fly with a left-footed volley that arrowed through a crowd of players and into the top of the net.
Slade's men were on a crest of a wave and Odubajo then turned supplier five minutes later as they doubled their lead.
James Tavernier was dragged out of position and that allowed the winger to slide the ball across goal for Cox to tap into an empty net.
The Millers desperately needed some inspiration and they almost found it on the stroke of half-time as Ben Pringle unleashed a 35-yard volley that dipped late, but landed on the roof of the net.
On the back of a verbal rocket from Evans at half-time, no doubt, the Millers finally stirred. Tavernier and Pringle both curled free-kicks narrowly over, before they reduced their deficit from a third set-play in the 55th minute.
Tavernier sent a delivery in which goalkeeper Jamie Jones spilled under pressure and Revell stabbed into an empty net.
If that was an easy goal Revell was to excel himself with his next effort five minutes later as he sensationally made it 2-2 with a goal that overshadowed Odubajo's.
A loose ball fell to him and from 30 yards, he took a touch and fired a looping 35-yard volley over the head of Jones and into the top corner for his 13th of the season and the third against his former club.
Orient were just grateful to weather the storm without further damage but they found their feet and began to threaten, with Kari Arnason's crucial intervention flying just over the bar, while Lloyd James' dangerous cross caused panic.
Evans' men came back and had two good chances to steal it in normal time, but top scorer Kieran Agard fired wide with a first-time effort and then headed over.
Extra time was low on quality meaning it was decided by penalties.
Jones put his side in the ascendency with a low save to keep out Lee Frecklington's effort, but Collin rescued his side with two saves to send the Millers into ecstasy.