McLaughlin-Levrone ran away from the rest of the field, posting a time of 50.37, easily breaking the Olympic mark of 51.46 she set in Tokyo three years ago and just ahead of the 50.65 she put up at the U.S. Olympic trials earlier this year.
Anna Cockrell of the U.S. was second at 51.87, with Femke Bol of the Netherlands in third at 52.15.
Both were well behind McLaughlin-Levrone, who was around 10 meters in front of everyone else when she hit the tape.