Kim Rhode became the first American to win individual medals at five straight Olympics by securing skeet gold.
Rhode, silver medallist in Beijing four years ago shot a world record-equalling 99 to finish eight points ahead of China's Wei Ning.
Slovakia's Danka Bartekova, whose world record of four years was matched by Rhode, took bronze.
She had to beat Russian Marina Belikova in a shoot-off for third place.
It is Rhode's third Olympic gold medal, with her first two coming in the double trap in 1996 and 2004, an event in which she also claimed bronze in Sydney 2000.
The 33-year-old Californian chose to switch to skeet after the double trap was dropped from the Olympic programme in 2004.