Johnson joined the faculty of the University of Wisconsin, in the Department of Economics, in 1957. He served as associate chairman and chairman of the department from 1962 to 1968. After a year of leave at the National University of Singapore, he returned to the Department of Economics at the University of Wisconsin and later became Dean of International Studies and programs from 1972 to 1980. He served simultaneously for two years as Director of the Industrial Relations Research Institute from 1978 to 1981 and as Director of the Center for Development from 1984 to 1988, when he retired from the university.