Born as Dorothy Penelope Jones in Dallas, Texas, her short film career began when she was visiting a cousin, who was working on a film for Fox Film Corporation in 1927. Her beauty was noticed at once and she was asked to make a screen test. Janis went on to make five films: four silents and one talkie.  The one talkie was Lummox (1930) based on the Fannie Hurst novel. This film, released by United Artists, only exists as a single nitrate print at the British Film Institute. Janis was best known for playing opposite Ramon Novarro in the MGM film The Pagan (1929), for which MGM publicity portrayed her as half-Cherokee. The Pagan, directed by W. S. Van Dyke, was a part-sound film, with music and sound effects only, and featured “Pagan Love Song” on the soundtrack.

Janis retired in 1930 and married bandleader Wayne King in 1932. The vice president of the Music Corporation of America, W. H. Stein, was best man. Janis and King were married for 53 years, until King’s death in 1985. She lived in Paradise Valley, Arizona from 2004 up until her death on March 10, 2010 at the age of 98. She was survived by her son, Wayne; her daughter, Penny Pape; 6 grandchildren and 11 great-grandchildren. She was laid to rest in the All Saints Episcopal Church Cemetery in Phoenix, Arizona.