Nyong'o took teaching positions at the
University of Nairobi, where he was a professor of
political science and a visiting professor in universities in
Mexico and
Addis Ababa. Here, he served until 1987, before taking up the position of head of programs at the African Academy of Sciences. He was a member of the Kenyan Senate representing
Kisumu County from March 4, 2013 to August 8, 2017 having been elected on an ODM (Orange Democratic Movement) Party ticket. He is a former Member of Parliament for
Kisumu Rural constituency, having been elected on a
NARC ticket in the December 2002. His political career dates back to 1992, when he was first elected to parliament. He served as a nominated MP from 1998 to 2002. From 2003 to 2005, Nyong'o served as the Minister for Planning and National Development, and from 2008 to 2013 he was the Minister for Medical Services. For his contribution to scholarship and democratization, Nyong'o received a German-African Award in 1995. From October to December 2013, Nyong'o was a Brundtland Senior Leadership Fellow at the
Harvard T.H. Chan School of Public Health. In this role, he taught a course in the Department of Global Health and Population titled "Leadership Development in Global Health and Policy-Making in Kenya: The Case of Four Parastatals." In 2023,
United Nations Secretary-General António Guterres appointed Nyong’o to his Advisory Group on Local and Regional Governments, co-chaired by
Pilar Cancela Rodríguez and
Fatimatou Abdel Malick. ==Personal life==