Dorothy Knowles was born in Unity, Saskatchewan on April 7, 1929. She was educated at the University of Saskatchewan under Eli Bornstein, at the Goldsmith School of Art and at the Banff Centre for Arts and Creativity. Knowles has also attended Emma Lake Artist's Workshops. She is best known as a landscape painter and has exhibited across Canada and the United States. Knowles was made a member of the Royal Canadian Academy of the Arts. In 1987, she was awarded the Saskatchewan Order of Merit and became a proud member of the Order of Canada in 2004. Knowles is the widow of William Perehudoff, a fellow painter who is associated with the Colour Field movement.
Two postage stamps depicting paintings by Knowles, The Field of Rapeseed, 1971 and North Saskatchewan River, 1971 were issued by Canada Post on April 7, 2006.