Born in Wales, Ontario, Keith Markell graduated B.A., with honours in history, from McGill in 1938. He took his theology degree from Presbyterian College in 1941, and was ordained the same year. He served in churches in Vancouver and Ottawa and began doctoral studies at University of Chicago. Markell joined the staff of the Presbyterian College in 1947 as lecturer in church history, and was promoted to a professorship in 1950. In 1960, when the College entered McGill's Faculty of Religious Studies, he was appointed Assistant Professor; at his retirement in 1980 he was an Associate Professor. Markell received his Ph.D. from Chicago in 1971, and wrote a number of works on Canadian Presbyterian history.