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, secured the title with seven shots remaining, shooting 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 and she comfortably won her first Olympic title in the discipline.
Chiara Cainero of Italy, the champion in Beijing, could only finish fifth in the final, 10 points adrift of Rhode.
Germany's three-time word champion Christine Wenzel had to settle for sixth at the Royal Artillery Barracks.
Team GB's Elena Allen was eliminated in the qualifying rounds, finishing in 14th place with a score of 60 points.
The former world record holder said: "Disappointed isn't the word to describe how I feel. I was shooting extremely well over the last four or five weeks and particularly coming close to this event.
"The only time we get to experience the crowd and the noise is when we have these big competitions and unfortunately the pressure got to me."