Maddock was born in Carbonear in 1862. He was the eldest son of Robert Maddock. His father was the owner of a merchant firm, J. & R. Maddock, located in Carbonear. Once Maddock finished schooling, he and his brother, John, took over the firm and renamed it J. & J. Maddock.[2]
In 1900, Maddock was selected as the Liberal Party candidate for Carbonear and was elected to the Newfoundland House of Assembly shortly after. He was re-elected again in 1904.