After earning the highest marks in CPE in the then Bondo District, he pursued his secondary education in Cardinal Otunga High School, Kisii from 1979 to 1984.
He holds a first class honors in Bachelor of Science Degree (BSc) in Electrical and Electronics Engineering from The University of Nairobi class of 1989 and a Master’s in Business Administration (MBA) in Management Information Systems (MIS) from The University of Nairobi.
Gumbo became the chair of the public accounts committee beating ODM's preferred candidate John Mbadi.
[3] In his capacity as chairman of the parliamentary Public Accounts Committee (PAC), Gumbo was at the forefront of questioning cabinet secretary Anne Waiguru over corruption allegations in the ministry of devolution and planning in the National Youth Service Scandal.
[6] [7] In 2015 before tabling the forensic report on the judiciary, Gumbo told the media that he had received death threats from unknown sources.
[8] In the same year he said that he would run for the Siaya gubernatorial seat in 2017 to unseat the incumbent Cornel Rasanga.