The collection, gathered over 30 years, is to go on the block next year in New York and London, The Times of London reported.
The auction house Christie's describes it as "the most important and comprehensive private collection of letters and books related to Winston Churchill ever assembled."
Christie's estimates the entire collection will bring in up to $7.5 million.
The items cover the range of Churchill's life, from a baby picture taken in 1875 to a Cuban cigar the former prime minister gave someone as a souvenir in 1963. They include the scheduling cards kept by his secretaries in World War II, including meetings with King George VI and the Casablanca Conference in 1943 with "Don Quixote" and "Sancho Panza," the codenames given U.S. President Franklin Roosevelt and his aide, Harry Hopkins.
One of the more unusual items is a book inscribed to a young BBC producer in 1938: "To Guy Burgess, from Winston S Churchill, to confirm his admirable sentiments." Burgess, 13 years later, defected to the Soviet Union.