Charlotte Dujardin said she was "absolutely over the moon" after adding the grand prix to her freestyle triumph in her first ever Dressage World Cup final in Lyon on Sunday.
Dujardin, who shot to fame by winning two gold medals at the London 2012 Olympics, triumphed in both events with Valegro - the horse that was so formidable at the Games two years ago.
The Gloucestershire-based Brit scored an outstanding 92.179 per cent in the final, with Germany's Helen Langehanenberg second with 87.3 per cent and Dutch rider Edward Gal third on 83.7. after breaking her own world record in the freestyle on Saturday.
She performed a new floor-plan routine and music that featured Land of Hope and Glory interspersed with chimes from Big Ben, and there was no doubting her dominance once again.
"Winning the grand prix and freestyle at my first World Cup final is just absolutely fantastic. I am absolutely over the moon," she said.
"It was so much fun in the arena. He (Valegro) gives me so much and that's all you can ask for. It is just fantastic to be able to have him. It's all a dream come true.
"Now that I've done this music once, hopefully it can only get better and I think this one could actually beat my Olympic music."
Dujardin is now the Olympic, European and World Cup champion and holds all three of dressage's major world records - grand prix, grand prix special and freestyle.
Meanwhile compatriot and fellow Team GB member Zara Phillips completed her first competition of the season on Sunday by claiming a ninth-place finish at the Symm International Horse Trials in Oxfordshire.
The 32-year-old competed in the intermediate class on her London 2012 horse High Kingdom, posting a combined score of 47.6 penalties following dressage, show-jumping and cross-country tests.