Mackenzie possessed five university degrees. He obtained three from the University of Toronto: B.A. 1895, LL.B. 1896, and M.A. 1897. After studying at the University of Chicago, Mackenzie proceeded to Harvard, receiving an M.A. Political Economy 1898 and a Ph.D. 1909.
Mackenzie led the Liberal party from 1919-1948. Canada's longest serving Prime Minister, Mackenzie held the office of Prime Minister during 29 December 1921 - 28 June 1926, 25 September 1926 - August 1930, and 23 October 1935 - 15 November 1948.
He died in Kingsmere, Quebec and is buried at Mount Pleasant Cemetery, Toronto, Ontario.