Ledecky, 25, was knocked down from the throne in the 400 meters freestyle at the 2019 World Cup by Ariarne Titmus, Australia, who also won Olympic gold last year.
Last month, Titmus also broke Ledecky’s world record.
Ariarne Titmus has chosen not to swim in the WC so there was no rematch.
And Ledecky’s victory time, 3.58.15 was a new championship record – but 1.75 seconds above the world record.
– It feels good, this is the fastest I’ve ever been to the World Cup. I am very happy with it and look forward to the rest of the week, she says to the news agency AP.
She says she has not received any extra motivation from Titmus taking over the world record.
– If I had not had the motivation before that, it would have been a problem, she says.
Ledecky’s gold is her twelfth individual World Cup gold in history.
Only 15-year-old Summer McIntosh, Canada, finished second, at 3.59.39, becoming the fourth woman in history for four minutes in the distance.
The US men’s elimination team won the team race 4×100 meters freestyle in 3.09.34, 1.46 seconds ahead of second place Australia.
Caeleb Dressel, who won five Olympic gold medals in Tokyo, three of which individually, gave the United States a flying start on the opening leg. Dressel has now taken 14 golds, including team caps, in World Cup history.