Morison was educated at St. Paul's School in Concord, N.H., and at Harvard University and, after further study abroad, returned to teach at Harvard for 40 years. Taking the view that the art of writing history had been all but lost by American writers, Morison tried to revive it with a technique that combined experience, observation, and research. To give authenticity to his writing, Morison undertook numerous voyages himself, sailed the ocean routes followed by Columbus, and during wartime served on 12 ships as a commissioned officer in the Naval Reserve. By the time of his retirement from the navy in 1951, he had reached the rank of rear admiral.

Morison's writings include: Maritime History of Massachusetts (1921); Admiral of the Ocean Sea (1942), a biography of Columbus for which Morison was awarded a Pulitzer Prize; John Paul Jones (1959), which also received a Pulitzer; The Oxford History of the American People (1965); the monumental History of U.S. Naval Operations in World War II, 15 vol. (1947–62); The Life of Commodore Matthew C. Perry (1967); and The European Discovery of America, The Northern Voyages (1971).