The 23-year-old Yavi crossed the finish line in a world-leading eight minutes 54.29 seconds - fourth fastest ever - for the victory, while the 32-year-old Chepkoech crossed in 8:58.98 for silver.
"Oh my God, I just found out this is the fourth fastest in history, I am really excited about that.
After finishing fourth at the past two world championships, the gold medal gives me additional motivation to train hard."
Faith Cherotich, a 19-year-old from Kenya, captured the bronze in a personal best 9:00.69 to become the first teenager to climb the world medal podium in the event.
In the last individual race of the championships, fans were treated to a thrilling event featuring nine of the world's 10 fastest women this year.
Persons:
Beatrice Chepkoech, Yavi, Cherotich, Chepkoech, Lori Ewing, Toby Davis
Organizations:
Kenyan, Tokyo Olympics, Budapest, Thomson
Locations:
BUDAPEST, Bahrain, Kenya, Eugene