Mbadiwe was born to the family of Mbadiwe Odum from Arondizuogu then under then Orlu division of present-day Imo State. His uncle, Igwegbe Odum was a former warrant chief. He started primary education at St Mary's Catholic School, Port Harcourt and finished early education at a government school in Aba. He then attended the Hope Waddell Training Institute, Calabar, Aggrey Memorial College, Arochukwu, of present-day Abia State, Igbobi College, Lagos and the Baptist Academy, Lagos. At Baptist Academy, Samuel Akintola and E.E. Esau were staff members while some of his mates at Igbobi were Taslim Elias, Horatio Thomas and Justice F.O. Coker. After his secondary education, he dabbled into trading establishing Mbadiwe Produce Association in 1937.
He left Nigeria to study at Columbia and the New York University for collegiate education. In 1941, with others students from West British African colonies, was founded ASA, African Studies Association, space to report abuses of colonialist administration. There, he helped to establish an African student's association, where he gained the attention of then-First Lady Eleanor Roosevelt, who received him and his organization in the White House.
After returning from the U.S., he started his own business and established a research institute on African Arts. He soon entered the Nigerian political scene and joined the National Council of Nigeria and the Cameroons. In 1951, he was elected into the Eastern Region House of Assembly, he was re-elected in 1954, and made minister for Lands and National Resources. In 1957, he was made the Minister for Commerce. However, his political success was to undergo a great challenge when in mid-1958 he and Kola Balogun attempted to remove Nnamdi Azikiwe as the leader of N.C.N.C.
Mbadiwe set up his own newspaper, The Daily Telegraph, as an organ of protest. He later re-joined the party and was appointed Minister for Trade and Communications and also served as a special adviser to the Prime Minister, advising on African affairs.
He was one time Minister of Lands, Minister of Trade and Commerce, and Minister of Aviation. He was also appointed as the first and so far, the only "Ambassador Extra-Ordinary and Plenipotentiary" of the Federal Republic of Nigeria. KO, popularly known as "Man of Timber and Calibre" was a larger than life character with awesome accolades; he was the Agadagbachiriuzo of Arondizuogu, the Ononenyi of Orlu, the Maye of Lagos, the great eagle around whose name many legends are spun.
He built and inhabited the landmark, The Palace of The People, at Ndianiche Uno commissioned by late Prime Minister Abubakar Tafawa Balewa in 1965.
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