Britain's Leslie Law has been awarded individual gold in the three-day event after Germany were stripped of their gold medal following an appeal.
The decision also means Britain's team bronze has been upgraded to silver, and Pippa Funnell takes individual bronze.
The appeal came after the Germans were given first place following their protest against against a 12-point penalty to Bettina Hoy.
Hoy was penalised for apparently crossing the start line twice.
Law admitted he had sympathy for Hoy, despite being upgraded to gold after her penalty points were re-instated.
"My heart goes out to her. It was not that her performance lacked. It was just an unfortunate error," he said.
FINAL MEDAL STANDINGS
1 Leslie Law (GB)
2 Kimberly Severson (USA)
3 Pippa Funnell (GB)
"But it's a great result for the Brits all round. I'm very pleased for everybody."
The Court of Arbitration for Sport (CAS), sitting in Athens, ruled Hoy should have suffered time penalties in Wednesday's show jumping final, costing her the individual gold and Germany the team title.
The decision means she drops out of the top three altogether.
"For a rider this is worse than a catastrophe but we must accept the decision," said Reinhard Wendt, head of the German equestrian team.
"All I want to do now is stand in the corner and howl."
Hoy was was unaware of the decision when it was announced as she was flying to Germany.
"She doesn't know yet," Wendt added.
France, initially awarded silver after the team event, are the new gold medallists with the United States upgraded to bronze.
French rider Nicolas Touzaint said: "Justice has been done. We have the feeling that the same rules apply to everybody.
"It's a brilliant gold medal, but unfortunately there will be no Marseillaise, no podium, no lap of honour."
The British team of Law, Funnell, Jeanette Brakewell, Mary King and William Fox-Pitt will now be awarded silver medals.
Team manager Will Connell said: "I hope it won't lead to bad blood. It certainly will not from our side.
"(Bettina Hoy) made a silly mistake, a mistake that all
riders are taught very early on in their career not to make.
"That is a great shame for Bettina and the Germany team but the sport must be run within the rules."