After attending the National Academy of Design and earning a position in a publishing firm, Dorothy decided to give up her career as an illustrator. Looking for more lucrative work, Dorothy set her sites on becoming a motion picture actress. With no previous acting experience, Dorothy applied for a position in the stock company at Vitagraph, signing a contract in the early teens. Her first film was a bit part in a thirty minute version of A Tale of Two Cities in 1911, which also featured future silent stars Norma Talmadge and Mabel Normand. She continued to make 70 films with Vitagraph and during these years she played opposite almost all of the Vitagraph comedians, including John Bunny and his successor Hughie Mack, as well as child star Bobby Connelly.
Like many stars of early film, Dorothy's career dwindled with the popularity of two-reelers. She would leave film altogether after the filming of Vitagraph serial The Secret Kingdom in 1917.
^"Marries Movie Actress" (PDF). New York Times. September 1, 1916. Retrieved 2009-01-01. "H.H. Hevenor, lumber dealer, first saw Dorothy Kelly on the screen."
^"In Memoriam Bessie H. Acker". Garden City News Online. Retrieved 2009-01-01. "Bess was born in New York City August 19, 1922 to silent screen actress Dorothy Kelly and Harvey Hevenor."
^"Dorothy's Change of Art" Cosmopolitan Magazine, May 1917. "Dorothy Kelly effected a quick change of art when she gave up her work as an illustrator to become a photo-play actress."
^"'Dot' Kelly, Quakeress". The Green Book. Retrieved 2009-06-21. "She went to the Vitagraph studio at Flatbush and made application for a position in a stock company. The first question fired at her was: 'Have you had any experience?' 'I have not.' replied Dorothy Kelly."