Karen Morley born Mildred Linton in Ottumwa, Iowa, Morley lived there until she was thirteen years old. When she moved to Hollywood, she attended Hollywood High School and later graduated from UCLA. After working at the Pasadena Playhouse, she came to the attention of the director Clarence Brown, at a time when he had been looking for an actress to stand-in for Greta Garbo in screen tests. This led to a contract with MGM and roles in such films as Mata Hari (1931), Scarface (1932), The Phantom of Crestwood (1932), The Mask of Fu Manchu (1932), Arsene Lupin (1933), Gabriel Over the White House (1933) and Dinner at Eight (1933). In 1934, Karen Morley left MGM after arguments about her roles and her private life. Her first film after leaving the studio was Our Daily Bread (1934), directed by King Vidor. She continued to work as a freelance performer, and appeared in Michael Curtiz’s Black Fury, and The Littlest Rebel with Shirley Temple. Without the support of a studio, her roles became less frequent, however she did play Mr. Collins’ wife Charlotte Lucas in Pride and Prejudice (1940), which was produced by MGM. The film was critically well-received, but it did not advance her career, as a result, Morley turned her attention to stage plays. In the early 1940s, she appeared in several plays on Broadway, including as Gerda in the original production of The Walrus and The Carpenter.

Her career came to an end in 1947, when she testified before the House Un-American Activities Committee and refused to answer questions about her alleged American Communist Party membership. She maintained her political activism for the rest of her life. In 1954, she ran unsuccessfully for Lieutenant Governor of New York on the American Labor Party ticket. After being blacklisted in Hollywood by the studio bosses, she was never able to rebuild her acting career. In the early 1970s, Karen Morley briefly resumed her acting career with guest roles in television series such as Kojak, Kung Fu, and Police Woman In 1993, she appeared in The Great Depression, a documentary TV series produced by Henry Hampton’s Blackside Productions in association with BBC2 and WGBH. In the series, she talked about how helpless she felt as a privileged Hollywood actress in the face of all the poverty and suffering that surrounded her. She also spoke of her experience making Our Daily Bread and working for King Vidor, whom she described as a conservative who thought that people should willingly help each other without government interference. In December 1999, at the age of 90, she appeared in the magazine Vanity Fair in an article about blacklist survivors. Karen Morley lived in Santa Monica, California, during her later years. Karen Morley died from pneumonia in Woodland Hills, California, at the age of 93, and was survived by two grandsons, a great-grandson, and a great-granddaughter.