Martin Joseph Hillenbrand grew up in Chicago. He graduated from the University of Dayton in 1937. He received a master's degree in 1938 and a doctorate in 1948 from Columbia University and did postgraduate work at Harvard. He entered the Foreign Service in 1939 as vice consul in Zürich. His next stop was Rangoon, Burma.
- 1950-1952 Head of the division of German Government and Administration at the State Department
- 1952-1956 First Secretary at the Embassy in Paris
- 1952-1954 member of the Bruce mission aimed to get the French National Assembly to ratify the EDC Treaty
- 1956-1958 US political adviser in Berlin
- 1958-1963 Director of the Office of German Affairs at the State Department being in particular from 1959 to 1963 deputy director then director of the Berlin task force
- 1963-1967 American Minister and deputy chief of mission in Bonn
- 1967-1969 Ambassador to Hungary
- 1969-1972 Assistant Secretary of State for European Affairs (Washington)
- 1972-1976 Ambassador to West Germany (sent by President Nixon)
Retiring from the State Department, he became the Director general of the Atlantic Institute for International Affairs in Paris, a post he held until 1982. Then he taught at the University of Georgia.