During the First World War he served in the United States Army Air Corps as a first lieutenant and bombing pilot.

Upon his return to Pennsylvania, he practiced law and was the director of public safety for the city of Pittsburgh in 1933 and 1934.

Denny was elected as a Republican to the Eighty-second Congress, defeating incumbent Democratic Congressman Harry J. Davenport in the Pennsylvania 29th district.

He was an unsuccessful candidate for reelection in 1952 when redistricting forced him into an election against incumbent Democratic Congressman Herman P. Eberharter in the 28th District.

He died in Buxton, Derbyshire, England and is buried at Allegheny Cemetery in Pittsburgh's Lawrenceville neighborhood.