Kosgei grew up in Elgeyo-Marakwet County, Kenya, and had six siblings. Aged 17, she began running training with her boyfriend and now husband Matthew Kosgei.
Career
Kosgei finished in the top two in eight of the first nine marathons that she ran. She came second at the 2016 Lisbon Marathon behind Sarah Chepchirchir, in a personal best time of 2:24:45. Her time was faster than the previous course record. In 2017, Kosgei won the Bogotá Half Marathon, and came third at the Copenhagen Half Marathon. She came second in the 2017 Chicago Marathon in a personal best time of 2:20:22. Her time was the sixth fastest ever time at the Chicago Marathon. Weeks later, she won the Honolulu Marathon, beating the course record by over five minutes. In 2018, Kosgei came second in the London Marathon behind Vivian Cheruiyot. After injuring herself during the Bogotá Marathon, Kosgei decided to run the Great North Run, in order to practice ahead of the 2018 Chicago Marathon. She finished the event second, behind Cheruiyot. Kosgei later won the Chicago Marathon, after breaking away from a group of two other Kenyans and three Ethiopians after of the race. She set a personal best time of 2:18:35. During 2018, Kosgei also won a cross country event in Eldoret, Kenya, and the Kalya Half Marathon in Kapenguria, Kenya. Kosgei won the 2019 London Marathon, becoming the youngest woman to win the event. This is the third best time in London after Paula Radcliffe in 2005 with 2:17:42 and Mary Keitany 2017 with the world record 2:17:01. At the 2019 Great North Run, Kosgei won in a course-record time of 1:04.28, 23 seconds faster than the previous half marathon world record set by Joyciline Jepkosgei. She won the 2019 Chicago Marathon on 13 October 2019in a worldrecord time of 2:14:04, an improvement of her personal best by more than 4 minutes. She beat the previous world record by 81 seconds, and was over six minutes ahead of second place Ababel Yeshaneh. Kosgei wore specially adapted Nike shoes, which have been alleged to have given her a 60-90 second advantage. In January 2020, Kosgei announced that she would be competing at the 2020 London Marathon in April, aiming to defend her title. In the same month, she was chosen to lead the Kenyan women's marathon squad for the 2020 Summer Olympics in Tokyo, Japan. The other athletes chosen in the squad were Cheruiyot and Ruth Chepng'etich, and it is scheduled to be Kosgei's first appearance at the Olympics. In February, Kosgei finished second to Yeshaneh at the Ras Al Khaimah Half Marathon. Kosgei's time of 1:04:49 was two seconds better than the previous world record. Kosgei and Yeshaneh's time of 30:18 after of the race was only one second slower than the best time set in a track 10,000m event in 2019.
