Denis riding in the House of Commons until his death in 1934.
Denis was re-elected in 1940, 1945, 1949, 1953, 1957, 1958, 1962, and 1963.
He was the Postmaster General from 1963 until the Post Office patronage scandal of 1964.
In the midst of the scandal, he was appointed to the Senate at the recommendation of Prime Minister Lester B.
Pearson and served until his death in 1991.
He was a reservist in the 2nd Battalion (Reserve) Châteauguay Regiment.
Parc Azellus-Denis in Montreal is named in his honour.