From 1945 onwards he worked for the Department of Social Welfare, eventually rising to become its director. In 1958 he resigned from the Civil Service to work full-time for the People's Action Party (PAP), becoming a key member and later vice-chairman of its Central Executive Committee. The following year he successfully contested the Kreta Ayer seat in the 1959 general election for the Legislative Assembly, and joined the first government of Prime Minister Lee Kuan Yew as Minister for Finance. Upon Singapore's independence on 9 August 1965, Goh became the nation's first Minister for the Interior and Defence. He subsequently served as Finance Minister (1967–70), Minister for Defence (1970–79) and Minister for Education (1979–80, 1981–84).