Russian Olga Kotlyarova's record had stood since 2004, but today it was broken by British Olympic runner-up Keely Hodgkinson.
At a competition in Manchester, she set a new best time by three hundredths of a margin.
Her time was almost six seconds better than Greek runner-up Eirini Vasileious.
The 20-year-old, who took Olympic silver in the 800m in Tokyo, was the third to set a British record in the past 24 hours.
Yesterday in Karlsruhe, Dina Asher-Smith set a record in the 60 meters indoors and Sam Atkin did the same in Boston in the 3,000 meters.
Hodgkinson's result is not an official world record as 600 meters is not an official distance according to the International Athletics Federation.