After practicing medicine for a short period in New Brunswick, he moved to the Kootenay region of British Columbia in 1898 serving a large rural territory.

In 1932, he was created a Knight of Grace of the Venerable Order of the Hospital of St. John of Jerusalem for his services to medicine.

A supporter of Sir Wilfrid Laurier, King was a Liberal candidate in the riding of Kootenay in the 1911 federal election but was defeated.

He served in that portfolio until 1922 when he was offered a federal Cabinet position by Prime Minister William Lyon Mackenzie King.

King became Minister of Public Works shortly before winning a by-election to enter the House of Commons of Canada as MP for Kootenay East.