He was a primary school teacher (1949) and later interpreter for the Eastern Provinces of Nigeria (1949–51) before receiving a Fulbright Travel Grant for undergraduate study in the United States.
On completion of his studies in political science and international relations, he taught and held administrative offices in various universities: teaching assistant and research associate, Harvard University, Cambridge, Massachusetts (1960–62); visiting lecturer, University of Vermont, Burlington, Vermont (summer 1962); assistant professor, Brown University, Providence, Rhode Island, (fall 1962); lecturer/senior lecturer, University of Ibadan, where he became professor (1965–88), head of department (1965–72), and dean of the Faculty of the Social Sciences (1966–68); Cadbury Visiting Professorial Fellow, University of Birmingham Center for West African Studies, Birmingham, UK (1972–73); founding vice chancellor, University of Maiduguri, Borno State, Nigeria (1975–79); visiting professor and head of department; dean, Faculty of Social Sciences and Director of the Center for Development Studies; and member of the Governing Council, all of the University of Cross River State, Uyo, Nigeria (1984–86).
With a political perspective inspired by Garveyism and Pan-Africanism, Essien-Udom (dubbed the "black power professor" by University of Ibadan students) was intensely public spirited and committed to institution building.
He is the author of Black Nationalism: a Search for Identity in America[2] and many journal articles and conference papers; co-editor with Amy Jacques Garvey, More Philosophy and Opinions of Marcus Garvey; general editor of the Frank Cass Africana Modern Library Series and the Ibadan University Press Political and Administrative Studies Series.
He is survived by his wife, Ruby; his son Nkeruwem; his brother Ikpong; his sisters Arit, Enoh and Ester; and a host of nephews, nieces, and other relatives.