Nicholas Kimeli first competed in the national 5000 meter championships in 2015. He was eliminated in the preliminary run. Just one year later, he had improved his 5000 meter time by 15 seconds to 13: 44.40 minutes. In June 2017 he finished fourth over 5000 meters at the Kenyan championships and then competed at the U20 African Championships in Tlemcen, Algeria, in addition to the 5000, also over the 10,000 meters. He won the gold medal over the latter route in 29: 52.15 minutes. Just three days later, he won the bronze medal over half the distance. In August he improved his 5000 meter time at ISTAF Berlin to 13: 11.58 minutes, which put him in second place at the meeting. A year later he qualified for the Kenyan squad for the Commonwealth Games in the Australian Gold Coast . There he ended up in ninth place in the final.
At a competition in Hengelo in June 2019, Kimeli set a new 5,000-meter best time of 12: 57.90 minutes. In September he finished third in the national eliminations for the World Championships in Doha and was then nominated for the World Cup. In this he qualified in fifth place for the final, in which he finished eighth three days later in 13: 05.27 minutes.
Kimeli trains in the village of Kaptagat , near his hometown Eldoret. The training camp in Kaptagat had to be temporarily closed during the COVID-19 pandemic . In 2020, at the Diamond League Meeting in Monaco in August, he set a new best time in 12: 51.78 minutes, with which he finished second in the competition behind Joshua Cheptegei , who set a new world record by a large margin.