His next triumph came at the Houston Marathon in 2019, which he followed up with another win in Ottawa that same year, racing to a personal-best 2:08:03
In his third marathon of 2019, he announced himself on the Abbott World Marathon Majors scene at the 2019 TCS New York City Marathon when he finished as the runner-up, crossing the line 23 seconds behind race winner and compatriot Geoffrey Kamworor.
Korir then endured two years of inactivity over the marathon distance during the COVID-19 pandemic, but returned to New York in 2021 where he faced another Kenyan with good pedigree in the shape of half-marathon world record-holder Kibiwott Kandie.
After running down the early leaders alongside his compatriot, Korir then pulled away to add a maiden victory to his 2019 second place, securing the Series XIII AbbottWMM title in the process.
His total of 41 points for the series was seven better that 2021 champion, Ethiopia’s Sisay Lemma, with another Kenyan, Vincent Kipchumba, finishing third on the leaderboard.