Hossein Rezazadeh set a new world record as he reclaimed his Olympic title in weightlifting's +105kg class.
Rezazadeh set a new best of 263.5kg in the clean and jerk - beating his own record of 263kg set last year.
Nicknamed the "Iranian Hercules", Rezazadeh finished with an overall total of 473.5kg, which also tied his previous overall world record.
Latvia's Viktors Scerbatihs took the silver medal while Velichko Cholakov of Bulgaria won bronze.
"An Olympic gold medal is a precious thing and it's important for me and my country. I trained very hard for it and Allah helped me," said the deeply-religious Rezazadeh, who held a copy of the Koran in one hand during the medal ceremony.
"I dedicate this medal to the people of Iran and everybody who has helped me. I can lift heavier weights - if I am healthy I will go to 500kg."
Already one of Iran's sporting stars, Rezazadeh is sure to return to another hero's welcome after securing his country's first medal of the Games.
After taking the gold in Sydney, he had a branch of Iran state bank named in his honour and was awarded the a "Badge of Courage" from Iran President Mohammad Khatami.
Ronny Weller's bid to become the first lifter to win five
medals in five Olympics ended in disappointment when the 35-year-old German injured his right shoulder on his opening lift.
And Norwegian Stian Grimseth caused a slight delay to proceedings when he had to be hoisted from the stage after collapsing.
Grimseth, who is 6 ft 2 in and weighs just less than twenty five stone, crumbled to the floor with what
appeared to be a strained thigh during his first attempt in the clean and jerk.
Medical staff strapped him into a stretcher - but could not lift the massive Norwegian from the stage.
It eventually took five people to push him to the edge of the platform - and five more to help get him to the floor.