The 27-year-old and her London 2012 horse Valegro earned a score of 87.975%
"Charlotte never ceases to amaze," said Carl Hester, who finished third behind Dujardin and Germany's Isabell Werth.
"She is undoubtedly one of the best riders in the world because of her feel, which is to do with timing. Timing is everything and she has it."
Valegro is co-owned by Hester and Roly Luard and there has been speculation since the Olympics that the horse would be sold for £3m or more.
Djuardin hoped that a syndicate could be formed to keep the 10-year-old gelding in Britain, allowing the Olympian's partnership with him to continue.
"It has been a fantastic year, a dream come true," said Dujardin, who won individual gold at Greenwich Park with Valegro this summer and was also part of Great Britain's Olympic title-winning team.
"I didn't think I would be doing this show, so it's a huge bonus."
