Marjorie Mix was born in Buffalo, New York in 1931. After graduating from Kensington High School in 1949, she attended the University of Michigan, where she earned her bachelor's degree in English in 1953. That same year, Mix returned to Buffalo and enrolled in the University at Buffalo Law School. She would later earn an M.A. in English (1967), and a Ph.D. in higher education (1971) from UB.
From 1963 to 1969, Marjorie Mix held a number of teaching and Graduate Assistant positions in the UB departments of English and Higher Education. In 1969, she became assistant provost in the UB Faculty of Educational Studies. Mix later became assistant dean in the UB Law School and would complete her juris doctor degree at UB in 1977. In 1980, Mix left the university to practice matrimonial and family law.