Professionally, Bromberg's most outstanding attribute was his facility with sensitive character roles; in his motion pictures he could take a standard, undistinguished supporting part and make it unforgettably sympathetic.

In Hollywood Cavalcade he portrays Don Ameche's friend who knows he will never get the girl; in Three Sons he is the lowly business associate who longs to be given a partnership; in Easy to Look At he is the once-great couturier now reduced to night watchman.

Bromberg's interest in theatricals began while attending Stuyvesant High School, where he was coached by director of drama and future Broadway producer Gustav Blum.

"[5] After graduating from Stuyvesant,[6][7] he attended City College of New York for two years[4] and then went to work to help pay for acting lessons with the Russian coach Leo Bulgakov, who had trained with Konstantin Stanislavski.

The versatile actor played a wide variety of roles ranging from a ruthless New York newspaper editor (in Charlie Chan on Broadway) to a despotic Arabian sheik (in Mr. Moto Takes a Chance) to the Alcade of Los Angeles (opposite Tyrone Power in The Mark of Zorro).

When Warner Oland, the actor who played Charlie Chan, died in 1938, Fox considered Bromberg as a replacement, but the role ultimately went to Sidney Toler.

He played a homespun detective in Fair Warning (1937), Fox's attempt to create an "American" counterpart to its Charlie Chan and Mr. Moto series.

"[11] In Republic's The Devil Pays Off (1941) Bromberg played, as reported by Film Bulletin, "the role of a ruthless but fear-ridden shipping magnate with a quiet intensity that is enormously effective.

Subpoenaed to testify before the House Committee on Un-American Activities in June 1951, Bromberg refused to answer any questions in accordance with his Fifth Amendment rights.