Born in Isiugwu village of Ohafia (now part of Abia State, Nigeria), Kalu first studied at Hope Waddell Training Institute in Calabar before moving to Canada, completing a BA at the University of Toronto (1967), MA in history at McMaster University (1968), and a PhD in history at the University of Toronto (1972).
[1] In 1974, Kalu took up a post in the Department of Religious Studies at the University of Nigeria, holding various teaching and administrative posts within the university's structures until 2001.
He then took up the Henry Winters Luce Professor of World Christianity and Mission at McCormick Theological Seminary, a post he held until his unexpected death in 2009.
[3] In 1997, Kalu was honored with an honorary Doctor of Divinity at Presbyterian College at McGill University.
In 2019, the Ogbu Kalu Center for Christianity and African Culture was established at Abia State University.