James Kwambai is a runner from Kenya, who specializes in marathons. He is a former Kenyan record holder in the event, with his personal best of 2:04:27 hours in 2009. At the time this made him the second fastest runner ever, behind Haile Gebrselassie.
He won the Marseille-Cassis Classique Internationale in 2002, breaking the course record by over a minute. In 2006 Kwambai won the Brescia Marathon and Beijing Marathon, which were his first two marathons. He also won the 2008 and the 2009 Saint Silvester Road Race.
He finished second at the 2008 Berlin Marathon, where Haile Gebrselassie set a new marathon world record. Kwambai's time was 2:05:36, that made him the seventh fastest ever marathon runner at the time. At the 2009 Rotterdam Marathon Kwambai again finished second (behind Duncan Kibet) in a time of 2:04:27, the third fastest ever marathon at the time. At the 2010 New York City Marathon he completed the race in 2:11:31, which brought him fifth place. He returned to defend his title at the Saint Silvester race in São Paulo but ended up in third place behind Marílson dos Santos and Barnabas Kosgei. In November 2011 he took the title at the JoongAng Seoul Marathon in a time of 2:08:50 hours, despite rainy conditions. He took on the city's other major race, the Seoul International Marathon, in March 2012 and ran his best race in three years, finishing in 2:06:03 hours to take second behind Wilson Loyanae. In November he competed at the 2012 JoongAng Seoul Marathon, won it convincingly and broke the course record by 2:23 minutes, with a time of 2:05:50 hours. He was back in form in Seoul in November 2013 as he won in 2:06:25 hours for third straight victory at the race (the first person ever to do so).