Before joining Parjatan Corporation, Hannan served as the director general of the Department of Archaeology.
In 1991, he joined the Ministry of Culture as an assistant secretary from the 9th batch of Bangladesh Civil Service (BCS).
Hannan served in different administrations including Bangladesh Road Transport Corporation and BCS (Administration) Academy.
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Also, he worked as the upazila nirbahi officer (UNO) of Shalla upazila in Sunamganj and Zakiganj upazila of Sylhet.
Hannan wrote three fundamental books on magistracy, criminal law, and land management.
He obtained his MSS degree from the University of Dhaka's Department of International Relations.