Chebet claimed his second consecutive Boston Marathon – the first man to defend his title since Robert Cheruiyot did so in 2008 – in an unofficial time of two hours, five minutes and 54 seconds, while Obiri took the honors in only her second official marathon.
Tanzanian Gabriel Geay came in second, finishing in 2:06:04, while Kenyan Benson Kipruto placed third in 2:06:06.
More than 30,000 athletes from all 50 states and more than 100 countries participated in the famed 26.2-mile course, starting in rural Hopkinton and finishing on Boylston Street.
This year’s race marked the 10-year anniversary of the double bombings that took place near the finish line, killing three people and injuring at least 264.
Obiri won the women’s elite race to claim her first Boston Marathon title in an unofficial time of two hours, 21 minutes and 38 seconds.
An exuberant Obiri, who finished sixth in the New York Marathon in November, was greeted at the finish line by her proud daughter.
Obiri is a two-time Olympic silver medalist, coming second in the 5000 meters at Rio 2016 and Tokyo 2020.
Ethiopian Amane Beriso came in second, finishing in 2:21:50, while Lonah Salpeter of Israel placed third in 2:21:57.
American Emma Bates finished fifth in 2:22:10.