The new time is 51.41 seconds. The last time the 22-year-old set a world record was during the Tokyo Olympics last year, with a time of 51.46.
During the Olympics, McLaughlin took gold in both the 400-meter hurdles and the 400-meter relay.
The new record was set at Hayward Field in Eugene, Oregon, where the World Cup kicks off July 15-24.
There, McLaughlin, teammate Dalila Muhammed and Dutchman Femke Paul were named as the best candidates in the 400-meter hurdles. The three are the fastest women ever in distance