Jade Jones won Britain's first ever taekwondo gold when she beat Yuzhuo Hou of China in the women's under-57kgs final at ExCeL.
Jones, 19, had produced a late rally to land her trademark headkick and stun world number one Tseng Li-Cheng of Chinese Taipei 10-6 in the semi-final.
However, the opening against Hou - who had beaten Jones in last year's World Championship final - was tense, as each fighter tested their range during a scoreless first two minutes.
A low blow from the Chinese fighter accrued a second penalty which resulted in a point for Jones towards the end of the second round, and another shot to the body on the buzzer made it 2-0.
The Briton continued to go on the offensive and opened up a 5-1 lead heading into the final 30 seconds, closing out a stunning 6-4 victory.
Jones said afterwards: "It's amazing. The crowd has just been amazing. Before I came out I was thinking that she took my World Championship final. That killed me for ages.
"So I wasn't going to let her beat me here in front of a home crowd.
"To be the first British athlete to win an Olympic gold (in taekwondo) is just amazing."
Turkey's Servet Tazegul won the men's taekwondo featherweight gold medal, beating Iran's Mohammad Baghrei Motamed in the final by a score of 6-5.
Tazegul, the world number one and Beijing bronze medallist, defeated Britain's Martin Stamper to reach the final and was the class act of the -68kg category.
His aggression and speed was too much for Motamed, who also lost to Tazegul in the final of last year's world championships in South Korea.
Rohullah Nikpai, who won Afghanistan' first Olympic medal with a bronze in Beijing, picked up another bronze through the repechage, along with American Terrence Jennings.