Jones, of Welsh ancestry, appeared on Broadway a few times, including 1933's Roberta and the short-lived 1934 revival of Bitter Sweet. He starred in many film musicals during the 1930s and 1940s. The best-known of these were Show Boat (1936), and The Firefly (1937) (in which he sang the popular "Donkey Serenade"), which became a signature song throughout his career. However, he is now best remembered as the romantic straight man to the Marx Brothers in their first two MGM productions: A Night at the Opera and A Day at the Races.
On the strength of his appearance in A Night at the Opera, however, he won the coveted role of Gaylord Ravenal in the 1936 film version of Show Boat(opposite Irene Dunne), right out from under the noses of such screen musical favorites as Nelson Eddy and John Boles, neither of whom was noted for his acting. This was to become Jones's most distinguished screen role, in which, under the direction of James Whale, he was to display dramatic acting ability as well as musical talent.
He made a brief appearance in the 1936 Nelson Eddy - Jeanette MacDonald film Rose Marie, singing music from Charles Gounod's Romeo et Julietteand Giacomo Puccini's Tosca, but according to Merchant of Dreams, Charles Higham's biography of Louis B. Mayer, Eddy, who apparently considered Jones a rival and a potential threat, asked that most of Jones's footage in Rose Marie be cut, including his rendition of the great Puccini aria E lucevan le stelle - and MGM agreed to Eddy's demand.
In 1940, he moved to Universal for two musicals, both with scores by immortal composers: The Boys from Syracuse, with the stage score (severely cut) by Richard Rodgers and Lorenz Hart, and One Night in the Tropics, with an original score by Jerome Kern and Dorothy Fields which produced no hit songs. Following those, he slipped to leads in B musicals, two at Paramount, then eight at Universal, including a re-teaming with Kitty Carlisle inLarceny with Music (1943). The same year, he briefly returned to A’s by guesting, as himself, in the Olsen and Johnson musical Crazy House, where he again performed "Donkey Serenade."
Jones' son is the popular singer Jack Jones.
Jones was never a dentist, as many websites report. He had an active singing career in movies, television, on the stage, and in nightclubs from 1929 until his retirement.
Allan Jones died in New York City, aged 84 from lung cancer. He was cremated and his ashes were given either to a friend or family.