South Korea's Jin Jong-Oh took gold in the Olympic men's 10m air pistol event at the Royal Artillery Barracks.
Carrying over a four-point lead from the qualification round, Jin rarely looked in danger of being caught.
He won with a score of 688.2 - 6.9 points shy of the world record.
Italy's Luca Tesconi's excellent form in the 10-shot final saw him recover from fifth place to snatch silver on 685.8 points, while Serbia's Andrija Zlatic took bronze with 685.2.
China's defending Olympic champion, Pang Wei, had a disappointing final, and dropped from second to fourth.
BBC Sport commentator David Oates's analysis
It was a thrilling final that went right down to the wire. The world number one did enough and he held his nerve and finished with a remarkable flourish. It really was magnificent shooting.
Jin, who won silver in the event at the Beijing Games four years ago in addition to gold in the 50m pistol discipline, came to London as one of the favourites, having won the Asian Championship earlier this year.
The 32-year-old, known as the 'Undaunted Man', held a 4.4-point lead at the halfway stage of the final but that was gradually cut to 1.3 as Tesconi, an Italian police officer, produced some fantastic shooting under pressure.
But with his last effort, a fantastically composed Jin - who will seek to retain his 50m title on 5 August - scored a near-perfect 10.8 points to wrap up victory.
He said: "I am very happy because it is a first gold medal for Korea, and personally it is very meaningful.
"I think getting off to a good start is important, and I hope this medal will be a spur and inspire Team Korea to more success at these Games."
The man expected to push Jin all the way, China's Tan Zongliang, earlier failed narrowly to qualify for the final.
After only finishing third in Beijing, Tan publicly apologised on Chinese television for his performance.
"I have let my country down," he said.