The American was officially elevated Thursday to shot put champion from the 2004 Athens Games, taking the gold that was stripped from a Ukrainian rival for doping.
The International Olympic Committee reallocated the medals from Athens events in which athletes were retroactively disqualified after their doping samples were retested and came back positive for steroids.
Nelson finished second in Athens behind Yuriy Bilonog, who was stripped of the gold medal by the IOC in December after his reanalyzed sample tested positive for oxandrolone.
The IOC held off changing the medals until the results were officially adjusted by the International Association of Athletics Federations. On Thursday, the IOC board announced that Nelson had been bumped up to the gold.
The medal will be given to the U.S. Olympic Committee to present to Nelson.
Nelson and Bilonog finished with the same best throw in Athens, but the Ukrainian was declared the winner because his second-best attempt was longer. It was the first time an Olympic field event was decided by a second-best mark.
Nelson recently retired from competition and is living in Athens, Ga., where he's opening a sports performance center and volunteering to help raise awareness for rare diseases.
"It's not just a victory for me, but a victory for the system," Nelson said in December when Bilonog was stripped of the medal. "I can't dwell on what happened or didn't happen eight years ago. I can only look forward to what the next phase in life brings. At least now I can do that with a gold medal."
As for his silver medal, Nelson said he tucked it away in a sock drawer years ago and thought his wife may have moved it to the attic.
With Nelson moving up to gold, the other medal placings are also revised. Joachim Broechner of Denmark goes from bronze to silver, and Manuel Martinez of Spain from fourth to bronze.
Bilonog's disqualification meant that both shot put winners in Athens were disqualified for doping: Women's champion Irina Korzhanenko of Russia was stripped of gold at the games after testing positive for stanozolol.
Bilonog was one of five Athens athletes busted in the retroactive IOC tests.
Also stripped were hammer throw silver medalist Ivan Tskikhan of Belarus and four bronze medalists—women's shot putter Svetlana Krivelyova of Russia, discus thrower Irina Yatchenko of Belarus and weightlifter Oleg Perepechenov of Russia.
The IOC said Yatchenko's medal will go to Vera Pospisilova-Cechlova of the Czech Republic, while Perepechenov's bronze in the 77-kilogram weightlifting class goes to Reyhan Arabacioglu of Turkey. There was no immediate word on the medals won by Tskikhan and Krivelyova.
The Athens Games were already considered the dirtiest on record, producing 26 doping cases and catching six medalists—including two gold winners—at the time. The retroactive tests brought the number of Athens cases to 31, including 11 medal winners and three gold medalists.
Since Athens, the IOC has been storing doping samples from each Olympics for eight years to allow for retesting when new detection methods become available.
Retesting of samples from the 2008 Beijing Olympics led to five positive cases—including the stripping of Bahrain runner Rashid Ramzi's gold medal in the 1,500 meters.
The IOC is preparing to retest samples from the 2006 Winter Games in Turin.