M. Clyde Kelly was born in Bloomfield, Ohio. He attended Muskingum College in New Concord, Ohio. He was engaged in newspaper publishing at Braddock, Pennsylvania, in 1903 and established the Braddock Leader in 1904.
In 1907 he purchased the Daily News and the Evening Herald and consolidated them into the Daily News-Herald. He was a member of the Pennsylvania House of Representatives from 1910 to 1913.
Kelly was elected as a Republican to the Sixty-third Congress, but was an unsuccessful candidate in 1914. After his term in Congress, he continued his newspaper work. He was again elected as a Progressive to the Sixty-fifth and reelected as a Republican to the eight succeeding Congresses. He was an unsuccessful candidate for reelection in 1934.
After his time in Congress, he resumed his former business pursuits. He was accidentally shot while cleaning a rifle and died in a hospital at Punxsutawney, Pennsylvania; he was interred in Mahoning Union Cemetery, near Marchand, Pennsylvania.