Illingworth Kerr studied at the Central Technical School, Toronto in 1924. From 1924 to 1927, Kerr studied under Arthur Lismer, J.E.H. MacDonald, Frederick Varley and J.W. Beatty at the Ontario College of Arts. Kerr also studied at the Westminster School of Art, London, in 1936, as well as with Hans Hoffman in Provincetown, Massachusetts in 1954. In 1955 and 1957, he attended Emma Lake Workshops.
Kerr traveled the Georgian Bay area, Ontario, in 1927, and England and France from 1960 to 1961. He taught at the Vancouver School of Art from 1945 to 1946, and was head of the Alberta College of Art from 1947 to 1967. He was a great influence and friend to many artists of that era. As well, from 1952 to 1953, he was president of the Alberta Society of Artists. Kerr was also a member of the Canadian Authors Association; he wrote many short stories and illustrated many publications, including his autobiography, Gay Dogs and Dark Horses, in 1946. He received a Canada Council Award in 1960.
He painted portraits, the life of Indigenous peoples, urban views, wildlife, and the Prairie and Ontario landscape. He used the media of oil, acrylic, watercolour, charcoal, and ink, as well as woodblock, linoblock, monotype and silkscreen prints.