James L. Massey served on the faculties of the University of Notre Dame, Indiana (1962-1977), the University of California, Los Angeles (1977-1980), and the Swiss Federal Institute of Technology (ETH), Zurich (1980-1998), where he now hold emeritus status. He is currently an Adjunct Professor at the University of Lund, Sweden.

He has served the IEEE Transactions on Information Theory as Editor and as Associate Editor for Algebraic Coding and the Journal of Cryptology as an Associate Editor. He is a past President of the IEEE Information Theory Society and of the International Association for Cryptologic Research. Massey was a founder of Codex Corporation (later a division of Motorola) and of Cylink Corporation, Santa Clara, California.

His awards include the 1988 Shannon Award of the IEEE Information Theory Society, the 1992 IEEE Alexander Graham Bell Medal "for contributions to the theory and practical implementation of forward-error-correcting codes, multi-user communications, and cryptographic systems; and for excellence in engineering education", and the 1999 Marconi International Fellowship.

He is a Fellow of the IEEE, a member of the Swiss Academy of Engineering Sciences and the U. S. National Academy of Engineering, an honorary member of the Hungarian Academy of Science, and a foreign member of the Royal Swedish Academy of Sciences.