In the 1970s, Mezu founded the Imo State branch of the Nigerian Peoples Party (NPP) and as Secretary of the NPP he installed and helped to elect to office Governor Samuel Onunaka Sam Mbakwe and other notable names.
He was Campaign Director, Party Secretary and principal architect of the NPP, which won a landslide victory (over 80%) in the Imo State Legislative, Gubernatorial and Presidential Elections in Nigeria in 1979.