[2] Mannan started his career when he joined the Department of Management of the University of Chittagong as a lecturer in 1973.

[3] He conducted advanced research on international commerce in Ohio State University in 1989.

[4] In 1996, Mannan became the youngest vice-chancellor of the country when was appointed at the University of Chittagong.

He then became an Advisor to the board of trustees and a full-time Professor in the Business School of the University of Liberal Arts Bangladesh (ULAB).

He also served as a professor in the Department of Business and the Dean of Faculties at the East West University.