Kipyegon shaved almost an entire second off the previous mark of 3:50.07 set by Ethiopia's Genzebe Dibaba in 2015.
The world record completes the 29-year-old's collection of feats, adding to her two Olympic 1,500m golds and the 2017 and 2022 world titles, Commonwealth Games gold medal from 2014 and three Diamond League titles.
Dina Asher-Smith, who won the world 200 metres title in Doha in 2019, pulled out in the build-up to the race.
Spaniard Mohamed Katir produced a lung-busting performance to win the 5,000m with a world leading 12:52.09, with world record holder Joshua Cheptegei coming in fourth.
Reporting by Aadi Nair in Nashik, India; Editing by Ken FerrisOur Standards: The Thomson Reuters Trust Principles.
Persons:
Pietro Mennea Golden, Luigi Ridolfi, Kipyegon, Remo Casilli FLORENCE, Fred Kerley, Ethiopia's Genzebe, Britain's Laura Muir, Jessica Hull, Muir, Ferdinand Omanyala, Trayvon, Jamaica's Yohan Blake, Jacobs, Ivorian Marie, Josee Ta Lou, Gina Lueckenkemper, Imani, Lara Lansiquot, Dina Asher, Smith, Ta Lou, Erriyon Knighton, Grant Holloway, Mohamed Katir, Joshua Cheptegei, Italy's Leonardo Fabbri, Andy Diaz, Larissa Iapichino, Aadi Nair, Ken Ferris
Organizations:
Diamond League, Commonwealth Games, Kenyan, Rabat, Thomson
Locations:
Florence, Italy, Ivorian, Doha, Netherlands, Rabat, Nashik, India