At the 2015 Athletics Kenya World Championship Trials he finished third in the 400 metres hurdles event.

[4] Later that year he represented Kenya in the 400 metres hurdles event at the 2015 World Championships in Athletics in Beijing, China.

Again in 2016 he finished third at the 2016 Athletics Kenya Olympic Trials behind his brother and Boniface Mucheru Tumuti.

At the Olympics, Koech made the final while his brother was disqualified in the heats.

Tumuti went on to capture the silver medal in National Record time, while Koech finished seventh.