Jordan Burroughs landed a $250,000 (£160,000) bonus after becoming the United States' first wrestling champion of London 2012.
World champion Burroughs, 24, beat Iran's Sadegh Goudarzi 1-0 1-0 in the 74kg freestyle event.
Before the Olympics,
promised to pay the cash to any American who won gold in the sport.
Uzbekistan's Soslan Tigiev and Russian Denis Tsargush claimed the weight division's two bronze medals.
Burroughs showed his confidence before the Games when he picked the Twitter name
while his website address is www.alliseeisgold.com.
The New Jersey wrestler only started competing in international tournaments less than two years ago, but he showed no sign of nerves against Goudarzi, the man he beat to win the world title in Istanbul last year.
Burroughs clinched the first period after taking the Iranian down.
The second period was locked at 0-0 until the American picked up Goudarzi and dumped him off the mat with barely 10 seconds remaining.
In his bronze medal match, European champion Tsargush beat Canada's Matthew Gentry, while Tigiev beat Gabor Hatos of Hungary.