James Horace King was born on January 18, 1873, in Chipman (Queens Co., New Brunswick) to George Gerald and Esther King (nee Briggs). He attended McGill University and earned a medical degree in 1895. He practiced in New Brunswick until 1898, when he moved to the Kootenays (British Columbia). In 1907, he married Nellie Mae Sadler (1876-1949). And, in 1951, King married Flora May Johnson (1881-1967).
In 1903, James Horace King was elected as a member of the Liberal party in British Columbia and served in the Legislative Assembly for Cranbrook riding. In 1916 he won a provincial seat, becoming a representative of the Legislative Assembly of British Columbia. In 1922, King joined the federal government with Prime Minister Hon. William Lyon Mackenzie King as the Minister of Public Works (1922-1926), later becoming acting Minister of Labour (1925-1926), Minister of Soldiers’ Civil Re-establishment (1926-1928), Minister of Health (1926-1928), and Minister of Pensions and National Health (1928-1930). In 1942, King became Minister without Portfolio (1942-1945) and Senator until his death on July 14, 1955.