Harold Town was born and raised in Toronto, where his father worked as a railway conductor in the west end Village of Swansea. From childhood, Town showed an obsession with drawing, using his family's kitchen table as his canvas. He studied art at Western Technical-Commercial School, where Renaissance art history and the Old Masters captured his imagination, before attending the Ontario College of Art from 1942 to 1944, though he found the teaching there uninspiring.

Town's artistic development was significantly influenced by Toronto's cultural institutions. As an OCA student, he received free admission to the Art Gallery of Toronto, where he felt challenged by great artists of the past and could emulate works like those of Edgar Degas by age twenty. The Royal Ontario Museum provided even greater inspiration through its Oriental prints, ceramics, Mesopotamian and Egyptian antiquities, and armor collections, giving him what he described as a global horizon that influenced both his commercial work and early experiments in abstraction.

After graduating in 1945, Town established himself as a commercial illustrator for advertising agencies and magazines including Maclean's and Mayfair. In 1953, he became a founding member of Painters Eleven, coining the name for this group of Toronto abstract artists that included Jack Bush, Oscar Cahen, William Ronald, and Jock MacDonald. The group, active from 1954 to 1960, helped introduce Abstract Expressionism to Canada and gained national recognition through joint exhibitions.

Town's breakthrough came through his printmaking innovations. Around 1953, he developed what he called "single autographic prints" (SAPs) - unique monotypes created with vivid colors and overlaying inks, sometimes enhanced with additional materials for texture and dimension. These prints gained international attention and led to his selection to represent Canada at the Venice Biennale in 1956 and again in 1964. Alfred Barr, director of the Museum of Modern Art in New York, called Town one of the world's greatest printmakers, and MoMA acquired his prints.

By the 1960s, Town had achieved significant recognition, earning record prices for a living Canadian artist and representing Canada at major international exhibitions including the São Paulo Art Biennial. He received numerous honors including an honorary doctorate from York University in 1966 and appointment as an Officer of the Order of Canada in 1968. His work encompassed painting, drawing, prints, collage, and sculpture, characterized by bold colors, technical virtuosity, and constant experimentation with different media and styles.

Town continued working until shortly before his death from cancer in 1990 at age 66. He had retrospective exhibitions at the Art Gallery of Windsor in 1975 and the Art Gallery of Ontario in 1986. Throughout his career, he remained based in Toronto despite criticism from some who felt he should have moved to New York, asserting his commitment to developing Canadian art on its own terms rather than following American trends.