Gregory Stephanopoulos was born in Kalamata, Greece, in 1950. Since 2006, he is the holder of the W. H. Dow Professorship of Chemical Engineering and Biotechnology at the Department of Chemical Engineering, Massachusetts Institute of Technology (MIT).

After graduation from NTUA he continued his studies in the United States. In 1975 he obtained his M.S. from the University of Florida and, three years later, his Ph.D. degree from the University of Minnesota. Professors Arnold Fredrickson and Rutherford Aris were his doctoral mentors. His professional career started in 1978 as Assistant Professor at Caltech where he was promoted in 1984 to the rank of Associate Professor with tenure. In 1985, Gregory Stephanopoulos moved to MIT as Professor of Chemical Engineering. He was Bayer Professor between 2000 and 2006, when he was appointed to the W. H. Dow Professorship of Chemical Engineering and Biotechnology. From 1990 to 1997 he served as Associate Director of the Biotechnology Process Engineering Center (BPEC) at MIT.  Since 1997, he has served as Lecturer on Surgery and Bioengineering for Harvard University at the Massachusetts General Hospital, while he spent the academic year 2006-2007 as Visiting Professor at the ETH Zurich.

The professional career of Professor Stephanopoulos is underscored by his prolific scientific production: he is the co-author of a book and the editor of five other titles, while he has written or co-authored more than 430 papers and is co-inventor of more than 50 patents. During his tenure, he has trained and supervised more than 150 Graduate and Post-Doctoral students; he presently serves on the Editorial Boards of 12 scientific journals (see CV for full list) and currently serves as Editor-in Chief of Metabolic Engineering (since 2003) and co-Editor–in-Chief of Current Opinion in Biotechnology (since 2010). Throughout his career he has served on the Advisory Boards of numerous Panels and Scientific Advisory Boards of government, academic and industrial organizations. Presently he serves on the Advisory Board of the Swiss NSF for National Centers for Competence in Research (NCCR), the Delft Process Technology Institute (DPTI), the University of Illinois Institute for Genomic Biology, the Board of Directors of the International Chemical Reaction Engineering (ISCRE), and the Institute for Systems Biology (ISB).

Professor Stephanopoulos currently works in Cambridge, at the Department of Chemical Engineering of MIT, focusing on biotechnology, specifically metabolic and biochemical engineering. He is the Director of the Metabolic Engineering Laboratory. His group of approximately 20 graduate students and post-docs conducts research on various projects aiming at the development of biological production routes to chemical products and biofuels. Another program is investigating cancer as metabolic disease.