Hester, 55, and 27-year-olds Charlotte Dujardin and Laura Bechtolsheimer topped the podium to win Britain's first ever Games dressage medal, with the Germans taking silver and the Netherlands claiming bronze.
Each of the three dressage riders beat their German equivalent to finish with a team average of 79.979. Germany finished with an average of 78.216.
Hester said: "It's been a very special moment for British dressage to get this medal because there has never been a medal let alone a gold one in our sport before.
"To get a gold one actually rocked it for us and for all of our fans.
"The Olympics is about beating everybody but Germany have dominated this sport for the last seven Olympics winning gold so it is doubly special to beat them here as well.
"We came here with expectations of gold because we were European champions last year but the Germans have regrouped with a great team.
"After our first rides it was a very narrow margin in the lead going into the second day, but the worse thing for us is we had to wait another four days to then finish our team competition off.
"You are stressed all the way to the first day, then you are in the lead, then you can relax for one day and then you have another three days of stress.
"None of us could have afforded a bad ride, and none of us did have a bad ride and we are all very happy."
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