Benjamin has been a member of the faculty of Osgoode Hall Law School since 1977, and has held numerous visiting academic positions: in the U.S. at the University of Chicago, University of Illinois, University of Utah, Northwestern University and Duke University in Hong Kong; in Israel at Tel Aviv University; in Australia at Monash, Deakin, Melbourne and Sydney universities; in Singapore at the National University of Singapore; in Germany at the University of Hamburg and in France at the faculté de droit et de science politique d'Aix-Marseille.

Benjamin has been a visitor at the law faculties of Oxford and Cambridge universities in England and at Max-Planck Institute for Comparative and Private International Law in Hamburg, Germany, as well as a Visiting Scholar at the United Nations Commission of International Trade in Vienna. He has been a Senior Research Fellow at the University of Vienna in Austria and a Senior Global Research Fellow at the Hauser Global Visitors Program of New York University School of Law.

Benjamin is the founding editor-in-chief of the Banking and Finance Law Review (BFLR) and the author of: a treatise on the law of electronic funds transfers, The Law of Electronic Funds Transfer, New York: Matthew Bender, 1992 (annually updated); a comparative law text book on bank collections and payment transactions, Bank Collections and Payment Transactions, Oxford: OUP, 2001; and a legal history monograph, The Payment Order of Antiquity and the Middle Ages, Oxford and Portland Oregon: Hart, 2011.

He is a member of the Committee on International Monetary Law of the International Law Association (MOCOMILA), Canadian Overseas Editor for the Journal of Banking and Finance: Law and Practice (Australia), member of the International Academy of Commercial and Consumer Law and a member of the Academic Advisory Board and External Professional Fellow of the Asian Institute of International Financial Law of the University of Hong Kong Law Faculty. He also worked for the International Monetary Fund.