Dunning began his career at age 12 as an extra and a carnival magician, and enlisted in the Navy during World War I.

[citation needed] Dunning collaborated with George Abbott to create Broadway, one of the most successful plays of the 1920s.

Dunning and Abbott produced Twentieth Century, the Ben Hecht-Charles MacArthur satire on the theater.

Dunning served in the Navy during World War II and produced the all-Navy show Biff!

He died of a myocardial infarction on the way to Norwalk Hospital and is interred in Assumption Cemetery, Westport, Connecticut.