Masuzoe was an academic assistant at the University of Tokyo from 1971, and later spent several years in Europe as a research fellow at the University of Paris (1973–75) and the Graduate Institute of International Studies in Geneva (1976–78). He was an assistant professor at the University of Tokyo from 1979 to 1989. After leaving the university in 1989, he established the Masuzoe Institute of Political Economy. He became known as a frequent guest on political talk shows in Japan, particularly the popular "TV Tackle" program hosted by Takeshi Kitano.