Biwott was a member of parliament for 28 years. In 1974 he ran unsuccessfully as a prospective MP for the Keiyo South Constituency. At the next election in 1979 he was successful, standing on KANU ticket in Keiyo-Marakwet, retaining the seat in 1983 and 1988. In 1992, 1997, and 2002 he was elected the MP for Keiyo South Constituency. In the Parliamentary elections held on 27 December 2007, running on a KANU ticket, he lost his seat to Jackson Kiptanui arap Kamai of the Orange Democratic Party (ODM). The ODM swept to victory in all but one of KANU's seats on the Rift Valley.