Double world champion Behdad Salimikordasiabi needed just four lifts to secure the gold ahead of Iranian teammate Sajjad Anoushiravani, sparking wild celebration among scores of raucous Iranian fans in the arena.
European champion Ruslan Albegov of Russia finished third.
Salimikordasiabi lifted 208 kilograms in the snatch portion and took 247 kilograms in his first attempt in the clean and jerk for a total of 455 kilograms.
No one even tried to challenge that score, so the Iranian giant used his second attempt in the clean and jerk to try for a world record. He loaded the bar with 264 kilograms — the weight of a golf cart — but gave up instantly and skipped his final lift.
Salimikordasiabi, 22, is undefeated in international competitions since 2009, winning world titles in 2010 and 2011 and sweeping four Asian championships from 2009-2012.
"Even though the two world championships are very good, the Olympic medal is something completely different," he said. "It's like the icing on the cake. It's the top thing, it's what I've always worked for."
The competition had an ugly moment when defending Olympic champion Matthias Steiner lost his balance trying to lift 196 kilograms in his second lift of the snatch portion of the competition. He fell awkwardly to the platform as the barbell crashed down on him.
Medical personnel rushed up to tend to the German, who got onto his feet and waved to the crowd as he walked into the back room. He didn't come out for his third attempt.
Michael Vesper of the German Olympic Committee said Steiner, who abandoned the competition at that point, was not seriously injured but was taken to hospital for checkups.
"It came to his neck, so for medical reasons he is not able to continue. But he isn't hurt badly," Vesper said. "Of course he was disappointed. He was not happy with the situation."
Harold Strier, a spokesman for Germany's weightlifting federation, said the German team doctor accompanied Steiner to the hospital.
"He is in a bit of pain in the back, and they don't want him to get a real heavy injury, and that is the reason he isn't starting again in the competition, and they have to look what happened," Strier said.
The medal winners said they hoped Steiner was OK.
"I just saw out of the corner of my eye that something happened out there," said Albegov, who beat Steiner at this year's European Championships.
"Then when I briefly saw him in the warmup area with the coaches around him and the doctor I realized it was really something serious," the Russian said. "I wish him health and some day I hope to see him again in competition."
The super heavyweight category wrapped up the weightlifting competition, which delivered 11 world records in 15 weight categories despite a series of high-profile withdrawals.
China topped the medal standings with five gold medals. Kazakhstan had four and North Korea three. Russia missed out on the gold but got five silver medals and one bronze.
Associated Press writer Jeremy Last contributed to this report.