William Winter was born in Winnipeg, Manitoba in 1909. He studied art under Frank H. Johnston and Lionel LeMoine Fitzgerald at the Winnipeg School of Art from 1923-1929.
From 1930-35 he worked as a commercial artist at Brigden's in Winnipeg.
In 1937, he moved to Toronto, Ontario and established an advertising firm with Lesley Wookey and Jack Bush in 1942. He created many painting cover illustrations for New World Illustrated.
In 1955, Winter abandonned his career in commercial art to focus on his personal art and establishing himself as a successful artist. His works often incoporated young children, and captured the beauty of youth. He gained national popularity after submitting a work with the Royal Canadian Academy, it was later purchased by The National Gallery.
By 1960 Winter had completed a number of mural commissions for organizations such as, the Canadian Pacific Railway, the Robert S. McLaughlin Public Library, the Standard Iron and Steel Company and the Children's Aid Society, among others.
During the 1960's, Winter taught drawing and painting at the Ontario College of Art and the Artist's Workshop, in Toronto. He also travelled and painted in Italy, Spain, Greece, and Mexico.
From 1994 onward he lived and worked in England. He died there in 1996.