It was a combination that rewrote the dressage record books for world-best scores, with that triple being among 10 gold medals they collected in Olympic Games, World and European Championships.
After Valegro’s post-Rio retirement, Dujardin concentrated on developing an exciting string of young horses led by Mount St John Freestyle and Gio, the 10-year-old gelding she will ride in Tokyo.
As a combination, Dujardin and Gio might have relatively few miles on the clock, but they posted a notable victory behind closed doors at the prestigious Hagen show in Germany last year.
Team success alongside six-time Olympian Carl Hester and Games debutant Charlotte Fry could ultimately offer Dujardin, 36, her best hope of a fourth Olympic gold at the Tokyo games.
If it happens, Dujardin would become only the second female British athlete to achieve that feat after cyclist Laura Kenny, and the competitive fires are burning brightly.
Dujardin told the PA news agency: “He is only 10, so he has done very little – probably six, or seven grands prix, at the most. He has done one grand prix special and one freestyle, so he is very inexperienced.
“But he seems to be coping with it all very, very well. He is definitely a trier, and I know he won’t go out there not to try.
“I have had him since he was five. I have trained him and En Vogue (Hester’s Tokyo ride), and it is a massive achievement to have both the horses out here.
“Both of them have now flown for the first time, and it’s obviously very different, but they have both handled it very well and training is going well.
“An Olympic Games is always my goal, which is why I have 10 or 11 horses in training, bringing them through the stages, so that I have always got one coming through for the Olympics.
“I have got a really good floor-plan for the freestyle (which decides individual medals), and who knows? On the day, you just don’t know.
“I will definitely give it a good go, and I won’t go down without a fight.”
Britain won team gold in London, then followed it up with silver at Rio, and Dujardin and 54-year-old Hester once again spearhead hopes of a podium hat-trick.
Germany, though, will take some stopping, with their team of Isabell Werth, Jessica Von Bredow-Werndl and Dorothee Schneider currently the world’s top three-ranked riders.
Werth, 52, is aiming to become the first rider to win seven Olympic golds, and just the third athlete to win gold at six different Games.
Dujardin added: “Carl has got the experience, and Lottie (Fry), yes it is her first Olympics, but I don’t think she gets fazed by anything.
“It is always incredible to be at an Olympics, and even though this one is a different one, it just brings home how great the team spirit is that we have.
“You realise how strong a team you have, and anything we need or the horses need, we get it.
“We’ve got a fantastic set-up in Tokyo, and we just feel very lucky to be here and doing it, really.”
Dressage starts at Tokyo’s Equestrian Park on Saturday, with team medals decided on Tuesday and the individual freestyle competition taking place 24 hours later.