He eventually left banking for the theatre, finding work with a stock company that led him to Chicago, Illinois, and another that toured the United States.

In 1924, he made his Broadway debut and worked off and on in the theatre for several years while supplementing his income by selling such products as car accessories, tea, insurance, real estate, and books.

His physical appearance and suave voice equipped him for roles as slick politician, corrupt businessman, crooked sheriff, or unscrupulous lawyer.

He was highly regarded by the studios, and was sought out by Cecil B. DeMille, Frank Capra, Hal Roach and other prominent Hollywood filmmakers.

He also played villainous roles in comedies, projecting a balance of menace and pomposity opposite the Marx Brothers, Abbott and Costello, and The Bowery Boys.

Dumbrille's wife Jessie Lawson, mother of their son John and daughter Douglass (Dougie), died in 1957 after 47 years of marriage.