He is the founding chairman Party of Independent Candidates of Kenya (PICK). He was the first director of the defunct Kenya Anti-Corruption Authority and ran as a Presidential Candidate in the 1992 Kenyan general election. Prior to his career as a politician, he was a sports shooter and competed at the 1968 Summer Olympics and the 1972 Summer Olympics.
Mwau vied for senatorial position for Makueni in 2013 Election. He was defeated by Mutula Kilonzo
2013 Makueni by-election
Makueni by-election, the first after the 4 March 2013 general election, was occasioned by the death of Mutula Kilonzo on 27 April 2013. The voter turnout was 60.4%.