Educated at Harvard University, he became a Massachusetts bank examiner after his graduation in 1912.
In London he supported the overtures of the Chamberlain government to Hitler and was generally noninterventionist.
He resigned as ambassador in November 1940, remaining aggressively isolationist in his views.
He wrote I'm for Roosevelt (1936).
Kennedy's wife, Rose Elizabeth Fitzgerald Kennedy, 1890–1995, was the daughter of U. S. congressman and Boston mayor John Francis"Honey Fitz"Fitzgerald. See A. Smith, ed. , Hostage to Fortune: The Letters of Joseph P. Kennedy (2000); biographies by R. J. Whalen (1964), D. E. Koskoff (1974), and D. Nasaw (2012); C. Beauchamp, Joseph P. Kennedy Presents: His Hollywood Years (2009); J. F. Dinneen, The Kennedy Family (1960), and D. K. Goodwin, The Fitzgeralds and the Kennedys (1987).
The founder of an American dynasty, he was the father of nine children, including John F. Kennedy, Robert F. Kennedy, Edward M. Kennedy, and Eunice Kennedy Shriver.