He has had a distinguished career as an internationally renowned economics professor, an economic adviser to the Japanese government and as an economic consultant to the IMF and WTO. He is currently Special Economic Adviser to Japanese Prime Minister Shinzo Abe, Tuntex Professor of Economics at Yale University and Professor Emeritus of Economics at the University of Tokyo. Japanese newspapers often refer to Hamada as “the brains behind Abenomics,” referring to his powerful, advisory influence on the Japanese Prime Minister’s economic policy. In 2006 he was awarded the imperial decoration, the Order of the Sacred Treasure, Gold and Silver Star, which is Japan\'s second-highest honour of its kind and the highest honour given to a civil servant.

Hamada has been Professor of Economics at Yale University since July 1986, and Tuntex Professor of Economics since December 2005. His current research topics include: international capital movements, regional integration, political economy of international monetary reform, economics and politics of Japan\'s last decade and a comparison of economic functions of the Japanese and the U.S. legal systems. His game-theoretic study of international monetary relations is regarded as one of the first studies that drew attention to the strategic aspects of macroeconomic policy in interdependent nations.

In 1997, Hamada served as a member of the external evaluation team of the Enhanced Structural Adjustment Facility (ESAF) Programme of the IMF Board of Directors. He then served as Senior Advisor for the Economic Research Institute of the Economic Planning Agency of the Japanese Government between 1998 and 2001. From 2001 to 2002, he was a member of the Consulting Group that advised Mike Moore, Director General of the WTO, on future perspectives for the world trade system, and in 2003 he also advised Supachai Panitchpakdi, Moore’s successor. Between 2001 and 2003, Hamada served as the first President of the Economic and Social Research Institute (ESRI), in the Cabinet Office of the Japanese Government.

He is an elected Member of the American Academy of Arts and Sciences and a Fellow of the Econometric Society, serving as council member from 1980 to 1985. President of the Japanese Association of Economics and Econometrics (now the Japan Economic Association) from 1994 to 1995, he was also the founding President of the Japan Law and Economics Association in 2003 (now its honorary fellow).

Hamada serves as associate editor for numerous journals including Econometrica, Journal of International Economics, Journal of Economic Theory, Journal of Public Economics, Journal of Development Economics and Journal of the Japanese and International Economies. His work on policy coordination, which first applied game theory to international finance, was published as ‘The Political Economy of International Monetary Interdependence’ (1985). Among his many other important published works are ‘Ageing and the Labour Market in Japan: Problems and Policies’ (2007), ‘Dreams and Dilemmas: Economic Friction and Dispute Resolution in the Asia-Pacific’ (2000) and ‘Strategic Approaches to the International Economy: Selected Essays of Koichi Hamada’ (1996).