Born into a family of show people, Blanche first appeared on the stage when she was 18 months old. Blanche was a dancer by the time she was four and a talented actress by 1909 when she started work at Biograph with D.W. Griffith . At 14, she was two years younger than Mary Pickford , but her maturity and appearance soon lead to leading roles. She starred in such films as The Lonedale Operator (1911) and Judith of Bethulia (1914). Unlike most of the frail roles for women of her day, her presence was smart and resourceful. She left Biograph in 1914 and worked with Cecil B. DeMille in The Warrens of Virginia (1915). A popular and independent actress, she worked for many studio's and directors in the age of silent movies. In 1922, she married director Marshall Neilan , who would direct her in Tess of the D'Urbervilles (1924). The marriage ended in divorce in 1929. In 1923, she starred in Anna Christie (1923), directed by John Griffith Wray , the first Eugene O'Neill (I) play to reach the screen. Even before the talkies appeared, her career was in decline. She made three talking pictures including Show Girl in Hollywood (1930). This was to be the last film that Blanche Sweet appeared in before retiring. Her line, in the movie, about being washed up at 32 in Hollywood was close to the truth for her. She was 34. After that she retired from the screen and returned to the Stage. She appeared in plays on Broadway and with touring companies and also worked in radio during the thirties. Blanche married one of her stage co-stars, Raymond Hackett , in 1936 and remained married until his death in 1958.

Off screen pseudonym: Daphne WayneCousin of players Florence Short , Gertrude Short and Antrim Short .She was named "Blanche" after her maternal grandmother, Blanche Alexander, who raised her.Daughter-in-law of Florence Hackett .Sister-in-law of Albert Hackett .Ex-stepmother of Marshall Neilan Jr. .In 1984 Blanche Sweet helped friend, producer Thomas R. Bond II re-establish the 'Biograph Company [us]' aka 'American Mutoscope & Biograph Co. [us]' which is the oldest movie company in America, established in 1895.