Business brought his father to New York City on several occasions, and eventually, five-year old Douglas, with his sister Hazel, were brought to America as second cabin class passengers, on board the British steamer Mauritania, which sailed from the Port of Liverpool on 29 October 1910, and arrived at the Port of New York, 4 November.

Douglas appeared in over 100 films from the late 1920s to the 1940s including The Great Gabbo (1929), Life Begins (1932), Men in White (1934), Madame X (1937), Cheers for Miss Bishop (1941), Now, Voyager (1942), Little Tokyo, U.S.A. (1942), Tall in the Saddle (1944), Murder, My Sweet (1944) and Show Business (1944).

One of his more prominent roles was also one of his last: In Gilda (1946), he plays the man who pretends to marry Rita Hayworth but is really a henchman of Glenn Ford's character.

[2] A review of The Black Castle in the trade publication Billboard complimented Douglas's handling of multiple roles in the drama.

Bob Francis wrote: "Except for the fact that he is inclined to ham the wizard, making the role often seem more silly than awesome, Douglas puts on a good 15 minutes.