Born Dorothy Walton Gatley at Fort Sam Houston in San Antonio, Texas, to George G. Gatley and Elizabeth "Bessie" Crabb. The daughter of a career army officer, she traveled often during her early life. Her father was born in Maine and served in the American Expeditionary Force in World War I. He died in San Francisco, California in 1931. The family finally settled in New York; Harding attended Bryn Mawr College in Bryn Mawr, PA, on thePennsylvania Main Line outside Philadelphia.
Following school, she found employment as a script reader. She began acting and made her Broadway debut in 1921. She soon became a leading lady, who kept in shape by using the services of Sylvia of Hollywood. She was a prominent actress in Pittsburgh theatre for a time, performing with the Sharp Company and later starting the Nixon Players with Harry Bannister. In 1929, she made her film debut in Paris Bound, opposite Fredric March. In 1931, she was nominated for the Academy Award for Best Actress for Holiday.
First under contract to Pathé, which was subsequently absorbed by RKO studio, Harding (who was promoted as the studio's 'answer' to MGM's superstar Norma Shearer), co-starred with Ronald Colman, Myrna Loy, Herbert Marshall, Leslie Howard, Richard Dix, and Gary Cooper, often on loan out to other studios, such as MGM and Paramount. At RKO, Harding, along with Helen Twelvetrees and Constance Bennett, comprised a trio who specialized in the "women's pictures" genre.
Her performances were often heralded by the critics, who cited her diction and stage experience as assets to the then-new medium of "talking pictures". Harding's second film was Her Private Affair, in which she portrayed a wife of questionable morality. The film was an enormous commercial success. During this period, she was generally considered to be one of cinema's most beautiful women, with her long waist-length blonde hair as one of her most noted physical attributes. Her films during her peak include The Animal Kingdom, Peter Ibbetson, When Ladies Meet,The Flame Within, and Biography of a Bachelor Girl. Harding, however, eventually became stereotyped as the innocent, self-sacrificing young woman. Following lukewarm responses by both her critics and the public to several of her later 1930s films, she eventually quit making movies when she married the conductor Werner Janssen in 1937. However, she returned in 1942 to make Eyes in the Night and to take secondary roles in other movies. In 1956, she again starred with Fredric March, this time in The Man in the Gray Flannel Suit.
The 1960s marked her return to Broadway after an absence of decades — she had last appeared there in 1927. In 1962, she starred in General Seeger, directed by and co-starring George C. Scott, and in 1964 she appeared in Abraham Cochrane. Both productions had brief runs, with the former play lasting a mere three performances (including previews). Harding made her last acting appearance in 1965 in an episode of Ben Casey before retiring from acting.
Harding married actor Harry Bannister in 1926. They had one child together before divorcing in 1932. Their daughter Jane was born in 1928 and died in December 2005. In 1937, Harding marriedWerner Janssen, the famous conductor. Janssen and Harding enjoyed life in a number of cities, before settling down in California to work more closely with Hollywood. The couple divorced in 1962. Her death certificate states that she had an adoptive daughter Grace Kaye Harding.
On September 1, 1981, Harding died at the age of 79 in Sherman Oaks, California. After cremation, her urn was placed in the Court of Remembrance wall at Forest Lawn Memorial Park in Hollywood Hills, California.
For her contributions to the motion picture and television industries, Harding has two stars on the Hollywood Walk of Fame located at 6201 (motion picture) and 6840 Hollywood Boulevard (television).