She represented her country at the World Under 20 Athletics Championships held in Cali, Colombia and finished in fifth place in the 3000m steeplechase race.

[3] On 18 February 2023 Kosgei won bronze at the 2023 World Athletics Cross Country Championships in the U20 women's race, finishing behind Ethiopians Medina Eisa and Senayet Getachew.

[7] In 2024, she moved to the U.S. and began taking summer classes at University of New Mexico with the intention of competing for the Lobos in Cross Country in the Fall of 2024.

In a New Mexico uniform, she ran a new personal best of 9:28.88 at the Portland Track Festival, taking second place to Allie Ostrander.

[8] In October 2024, she broke the course record set by Parker Valby to win the 2024 Wisconsin Pre-Nationals at the Thomas Zimmer Championship Cross Country Course in Madison.