John Young Johnstone was born in Montréal, Quebec. He studied at the Arts Association of Montréal alongside William Brymner, and then studied at the Grande Chaumière Academy in Paris under Castelucheo, L. Simon and R. Menard.
He travelled through Switzerland, France and Belgium.
Johnstone worked in many mediums, his subjects varied, he is best known for his landscapes, urban scenes, and portraits.
His work gained popularity in 1911 following one of his first exhibits at the Art Association of Montréal.
From 1918-1928, he taught at the National Monument School.
From 1915-1923 Johnstone exhibited with the Royal Canadian Academy, he became an academician in 1920. From 1911-1925 he was a member of American Association of Museums.
He died in 1930, in Havana, Cuba.
His works are included in many private and public collections, The Canadian Museum of Fine Art, among others.