Blewett was educated at the University of Tasmania, and won a Rhodes scholarship to attend Oxford University in 1957. He received his PhD in politics from London University, and held a position as Professor of Political Theory and Institutions at Flinders University of South Australia until 1977, when he ran for parliament as an ALP member. His political career included serving as a Minister in the Labor governments under Bob Hawke and Paul Keating from 1983 until his retirement in 1993 . He received an honorary Doctor of Law from the Australian National University in 2003.