Green Bay won their fourth Super Bowl with a thrilling 31-25 win over Pittsburgh in Texas.
Aaron Rodgers threw two touchdowns and Nick Collins returned an interception to give the Packers an 18-point lead shortly before half-time.
Two Steeler touchdowns reduced the lead to four but Green Bay pulled ahead when Greg Jennings scored his second.
Mike Wallace caught a 25-yard pass to bring Pittsburgh within three points but the comeback was not to be.
The Steelers, six-time Super Bowl winners, will look back on the contest with huge regret after three turnovers cost them 21 points.
Although no team has come back from more than 10 points down to win an NFL title game, Pittsburgh looked like doing so against the injury-hit Packers during the third quarter.
But Green Bay held on, joining the 2006 Steelers team as the only sides to have won the Super Bowl after entering the play-offs with the lowest seed in their conference.
RODGERS VS ROETHLISBERGER
Cowboys Stadium was a sea of yellow at kick-off with Pittsburgh and Green Bay fans turning out in full force amongst a crowd of 103,219 to create a fantastic atmosphere.
However, the organisers missed out on their aim of a record attendance by 766 after some fans had to be turned away because temporary stands were not ready, following a week of unseasonably cold weather.
After a cagey opening, the game exploded into life when 27-year-old Rodgers' perfect 29-yard pass to receiver Jordy Nelson gave his side a 7-0 lead towards the end of the first-quarter.
And Green Bay - who had not played in the Super Bowl since losing to the Denver Broncos in 1998 - were pinching themselves just 24 seconds later when they doubled the lead.
Under huge pressure from the Packer defence, Pittsburgh quarterback Ben Roethlisberger was hit as he attempted a long pass to Mike Wallace and was intercepted by free safety Nick Collins, who returned the ball 37 yards for a touchdown.
With Pittsburgh reeling and two-time Super Bowl winner Roethlisberger struggling with a knee injury, the omens did not look good for coach Mike Tomlin's team despite getting on the scoreboard on their following possession with a 33-yard field goal.
Things got worse for the Steelers when, on a promising drive after stopping the Green Bay offence, Roethlisberger was intercepted for the second time by cornerback Jarrett Bush.
Rodgers - named the game's most valuable player after completing 24 of 39 pass attempts for 304 yards and three touchdowns - was in full flow and looked like making a mockery of pre-game predictions of a slender Green Bay victory when he completed a 21-yard pass to Greg Jennings to give his team a 21-3 lead.
Pittsburgh desperately needed to score before the interval and Roethlisberger, nicknamed Big Ben because of his 17-stone frame, duly delivered with a 77-yard drive which was completed when Hines Ward made a leaping catch for an eight-yard touchdown.
After hip hop group the Black Eyed Peas dazzled the crowd with a typically outlandish performance, the second half saw the tide begin to turn in Pittsburgh's favour.
Fourth-year receiver James Jones gave the Steelers a reprieve when he dropped a simple third-down pass which would have almost certainly led to a touchdown and, on the following possession, Roethlisberger's offence took full advantage.
The Packers allowed an average of 114.9 rushing yards per game in the regular season but Pittsburgh would run for 50 on this drive alone to reduce the deficit to four points at 21-17.
It's what I dreamt about as a little kid, watching Joe Montana and Steve Young
Steelers fans were making themselves heard and the Packers were rocking in the face of huge pressure from the Pittsburgh defence, and when James Harrison sacked Rodgers the momentum had well and truly shifted.
But Steelers kicker Shaun Suisham missed a tough 52-yard field goal attempt and the defences were back on top for the remainder of the third quarter with neither side able to make much progress up the field.
The defining moment of the game would come right at the start of the fourth quarter.
With Pittsburgh in excellent field position, linebacker Clay Matthews forced a fumble from Rashard Mendenhall which was recovered by the Packers.
The Steelers' head of steam was well and truly halted and when Rodgers completed an eight-yard pass for Greg Jennings's second touchdown of the game the Packers had an 11-point lead with only 12 minutes to play.
An inch-perfect Roethlisberger throw to Mike Wallace gave the Steelers hope with seven minutes remaining and a two-point conversion from the touchdown reduced the deficit to three.
Mason Crosby scored a 23-yard field-goal with only two minutes remaining to extend that lead and leave Roethlisberger, 28, and the Steelers needing a touchdown
But when the veteran could not complete his pass to Wallace on fourth down and five, the Packers knew that the Vince Lombardi Trophy was returning to Green Bay for the first time in 14 years, sparking jubilant scenes.
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