While she never discouraged rumors that her mother, Katharine ("Kay") Gibbs, was a pioneering businesswoman who established the "Katharine Gibbs" chain of vocational schools, Francis was actually raised in the hardscrabble theatrical circuit of the period. Her mother was actually a moderately successful actress who used the stage name "Katharine Clinton." In later years, confusion over her origins and upbringing, in tandem with her raven hair and relatively dark complexion, led to the emergence of rumors that some of her ancestors were African American. Her mother's maiden name (Franks) led some to believe she was of Jewish descent.
Young Kay was out on the road with her mother, and attended Catholic schools when it was affordable, such as when she was a student at the Institute of the Holy Angels at age five. After attending Miss Fuller’s School for Young Ladies in Ossining, New York (1919) and the Cathedral School (1920), she enrolled at the Katherine Gibbs Secretarial School in New York City. At age 17, Kay became engaged to a well-to-do Pittsfield, Massachusetts man, James Dwight Francis. Their December 1922 marriage at New York’s St. Thomas Church was not to last.
By February 1927, Francis returned to Broadway in the play Crime. Sylvia Sidney, although a teenager at the time, had the lead in "Crime" but would later say that Kay stole the show.
After Kay’s divorce from Gaston, she became engaged to a society playboy, Alan Ryan Jr. She promised Alan's family that she would not return to the stage, however, her promise only lasted a few months and she was back on Broadway as an aviatrix in a Rachel Crothers play, Venus.
Francis was only to appear in one other Broadway production, a play called Elmer the Great in 1928. Written by Ring Lardner and produced by George M. Cohan, Walter Huston was the star. He was so impressed by Francis that he encouraged her to take a screen test for the Paramount Pictures film Gentlemen of the Press (). Francis made this film and the Marx Brothers film The Cocoanuts (1929) at Paramount's Astoria Studios in New York.
A combination of striking dark beauty, stature, and a deep, supple voice ideally suited to early sound-reproduction technology made Francis one of the top film stars of the early 1930s. So striking were her looks and screen presence that Francis was widely publicized as the epitome of the "American glamour girl" throughout the 1930s. Her success came in spite of a minor, but distinct speech impediment (an inability to pronounce the letter "r") that gave rise to the nickname "Wavishing Kay Fwancis."
Francis' career at Paramount changed gears when Warner Brothers promised her star status at a better salary. Nonetheless she did some fine portrayals in such films as George Cukor’s rollicking Girls About Town (1931) and the dark melodrama Twenty-Four Hours (1931). After Kay’s career skyrocketed at Warners, she would return to Paramount for Ernst Lubitsch's Trouble in Paradise ().
In 1932, Warner Brothers persuaded both Francis and Powell to join the ranks of Warners stars, along with Ruth Chatterton. In exchange, Francis was given roles that allowed her a more sympathetic screen persona than had hitherto been the case - in her first three featured roles she had played a villainess. For example, in The False Madonna she played a jaded society woman nursing a terminally ill child who learns to appreciate the importance of hearth and home.
Francis had married writer-director John Meehan in New York, but soon after her arrival in Hollywood, she consummated an affair with actor and producer Kenneth MacKenna, whom she married in January 1931. When MacKenna's Hollywood career foundered, he found himself spending more time in New York, and they divorced in 1934.
In the period of her greatest popularity she frequently played long-suffering heroines, in films such as I Found Stella Parrish, Secrets of an Actress, and Comet over Broadway, displaying to good advantage lavish wardrobes that, in some cases, were more memorable than the characters she played -- a fact often emphasized by contemporary film reviewers. Too frequently, however, Francis' clotheshorse reputation led Warners to concentrate resources on lavish sets and costumes, designed to appeal to Depression-era female audiences and capitalize on her reputation as the epitome of chic, rather than on scripts.
Eventually, Francis herself became dissatisfied with these vehicles and began openly to feud with her employers, even threatening a lawsuit against them for inferior treatment. This in turn led to her demotion to programmers such as 's Women in the Wind and, in the same year, to the termination of her contract.
After her release from Warners, Francis was unable to secure another studio contract. Carole Lombard, one of the most popular stars of the late 30s and early 1940s (and who had previously been a supporting player in Francis' film, Ladies' Man) tried to bolster Francis' career by insisting Francis be cast in In Name Only ().
In this latter film, Francis had a supporting role to Lombard and Cary Grant, but wisely recognized that the film offered her an opportunity to engage in some serious acting. After this, she moved to character and supporting parts, playing catty professional women - holding her own against Rosalind Russell in The Feminine Touch, for example - and as mother to rising young stars such as Deanna Durbin.
With the start of World War II, Francis plunged into volunteer work, including extensive war-zone touring, which was first chronicled in a book attributed to fellow volunteer Carole Landis, Four Jills in a Jeep. The book became a popular film of the same name, with a cavalcade of stars and Martha Raye and Mitzi Mayfair joining Landis and Francis to fill out the complement of Jills.
Despite the success of Four Jills, the end of the war found Francis virtually unemployable in Hollywood. She signed a three-film contract with Poverty Row studio Monogram Pictures that gave her production credit as well as star billing. The results — the films Divorce, Wife Wanted, and Allotment Wives — had limited releases in and . While more lavish than some Monogram productions, they were pale copies of her earlier work.
Francis spent the balance of the 1940s on the stage, appearing with some success in State of the Union and touring in various productions of plays old and new, including one, Windy Hill, backed by former Warners colleague Ruth Chatterton. Declining health, aggravated by an accident in 1948 in which she was badly burned by a radiator, hastened her retirement from show business.
While some acquaintances paint a lurid picture of a reclusive, hopelessly alcoholic decline in the 1960s, others describe Francis as content with a quiet life in her comfortable Manhattan apartment, enjoying the company of a small group of old friends.
In 1966 Francis was diagnosed with breast cancer and underwent a mastectomy, but the cancer had spread and proved fatal. Having no immediate survivors, Francis left over $1,000,000 to a company, Seeing Eye, Inc., which trained guide dogs for the blind.