The son of a prominent American historian of the same name, Arthur Meier Schlesinger, Jr. was born in Columbus, Ohio, on October 15, 1917. Graduating from Harvard University in 1938, he was a member of the University's Society of Fellows from 1939 to 1942. After serving with the Office of War Information (1942-43) and the Office of Strategic Services (1943-45) during World War II, he became a professor at his alma mater from 1946 to 1961.

An active Democrat, Schlesinger co-founded Americans for Democratic Action and worked in Adlai Stevenson's two unsuccessful Presidential campaigns.

In 1960, Schlesinger worked for John F. Kennedy's campaign and, in 1961, was appointed special assistant to the President for Latin American affairs. Resigning in 1964, after Kennedy's assassination, he became the Albert Schweitzer Professor of Humanities of the City University of New York, and was appointed chairman of the Franklin Delano Roosevelt Four Freedoms Foundation. .

Schlesinger has been a prolific writer and contributor to scholarly and popular periodicals. Among his books are The Age of Jackson (1945), which won a Pulitzer Prize for history; the multi-volume The Age of Roosevelt (1957-1960); and A Thousand Days (1965), a Pulitzer Prize- and National Book Award-winning history of the Kennedy Administration.