Charlotte Dujardin won Britain's second dressage gold medal of the Olympics as the host nation's equestrian team finished London 2012 with three titles.
"I wanted to enjoy it, go out and not regret anything," said Dujardin, who also helped Britain to team victory in Greenwich Park on Tuesday.
Dujardin beat a huge score from Dutch rider Adelinde Cornelissen while Laura Bechtolsheimer took bronze for GB.
Theirs are the first individual Olympic dressage medals ever won by Britain.
Dujardin, 27, partnered Valegro to victory as the two performed to movie themes including The Great Escape and Live And Let Die.
"It is always something I've known the horse could achieve, but I didn't really know how I was going to find the atmosphere and the expectation," she said.
"I love doing freestyle and I had great fun. Valegro felt tired but he went out there and gave it his all, he didn't let me down.
"He's 10 years old and given me three amazing rides, I couldn't have asked any more of him."
Bechtolsheimer, also 27, was the first of three Britons to ride in Thursday's final, scoring 84.339 with Mistral Hojris to guarantee Britain a medal.
Carl Hester, Dujardin's mentor of many years, then posted 82.857 on Uthopia, which proved good enough for fifth.
But the showdown for gold came down to the last two riders. Cornelissen upped the ante spectacularly with a huge score of 88.196 on Parzival, throwing a dramatic gauntlet down for Dujardin as the last rider into the arena.
Picked out against the London skyline beyond Greenwich's open-air arena, Dujardin scored 90.089 - an Olympic record, her second of the Games - to take gold.
Unprecedented success at London 2012 marks the beginning of a new era for British dressage, but also the end of one for the riders involved.
Hester's Uthopia and Dujardin's Valegro are both now due to be moved on by their owners, so the pair will have to find new rides if they plan to defend their titles at Rio 2016. Bechtolsheimer's Mistral Hojris, nicknamed Alf, may be retired, but she says she will give him time before making a decision.
"I was hoping Alf would come home with a medal today for that performance," said Bechtolsheimer. "He's 17 years old and he's given me so much. He was just beautiful to ride, so powerful to ride. He was doing it for me.
"At the end of the day, it's not a bike, it's not a tennis racquet, it's a living animal that you've worked tremendously hard to have a partnership with."
Hester said: "It's been an emotional and long year for us to keep the horses going. Without the horse, we're nothing.
"I always said Charlotte was the gold medallist. Valegro is the best horse in the world, just the consummate professional."
Dujardin's mother, Jane said as she watched her daughter collect gold: "All the pressure was really on her. What can I say? I'm just so proud.
"We never had the financial backing at all. When my mum died, I was lucky enough to have some inheritance money and I knew I had to buy Charlotte a horse. She could make a donkey do anything. I managed to get hold of Carl and put her in the right hands from there on in."