Harold Williamson was born in Leeds. He studied at the Leeds School of Art, 1911-1914. The following year he attended the Royal Academy Schools in London and was awarded the Turner Gold Medal.
Following the outbreak of war, he attempted to enlist in the army, but was turned down on health grounds. In 1916 he was accepted as a rifleman and was injured at the Battle of Delville Wood. Whilst recuperating he was recruited to the War Artists Scheme for the Ministry of Information but the Armistice meant that the contract was not taken up.
After the war he designed for several commercial organisations including London Transport and exhibited at the Royal Academy. Between 1930 and 1958 he was Headmaster at the Chelsea School of Art, employing Henry Moore as head of a new sculpture department in 1932.