Onuma Uko was born in the village of Ohafia Bende, Nigeria, and educated first at mission schools. She received her B.A. from Bennett College (Greensboro, North Carolina) in 1958. In 1958, she married Kalu Ezera, a political scientist with a 1957 Oxford D.Phil. and a prominent figure in Nigerian and Biafran politics. After teaching history at St. Anne's Secondary School (Ibadan) and serving as principal at the University of Nigeria Primary School, Onuma Ezera joined the University of Nigeria, Nsukka. as a librarian in charge of Readers' Services, Circulation and Reference. She enrolled in 1967 in the masters program in librarianship at the University of Washington, earning her MLS. Her return home was interrupted by the worsening of the Biafran War, and her four sons joined her in East Lansing where she took a "temporary" job at Michigan State University, the institution that had helped set up the University of Nigeria. The tragic disappearance of her husband at the end of the Biafran War prolonged her stay at MSU where she had a distinguished career.