McNicoll was born in Toronto to an affluent family. Her parents were David McNicoll and Emily Pashley. McNicoll became deaf in early childhood due to scarlet fever, and as a result, focused her energies on playing the piano and developing a keenly observant eye. As a young woman, she attended the Art Association of Montreal, beginning her studies under William Brymner in 1899. In 1902, she moved to England to study in London at the Slade School under Philip Wilson Steer. At the Slade, students were encouraged to paint en plein air. Later, McNicoll studied in St Ives, Cornwall with Algernon Talmadge, where she met Dorothea Sharp, a fellow artist who became a lifelong friend. McNicoll and Sharp traveled together to France and Italy sharing studio space, and posing for each other's paintings.
A member of the Royal Society of British Artists and an associate of the Royal Canadian Academy of Arts, McNicoll died in Swanage, Dorset, at the early age of thirty six. An obituary described her as "one of the most profoundly original and technically accomplished of Canadian artists."
The Art Gallery of Ontario hosted an exhibition of McNicoll's work in 1999. Although she had relocated to England, during her lifetime McNicoll kept close ties to Canada, and her work was exhibited at the Royal Canadian Academy of the Arts from 1906 to 1914. Her work was also exhibited at the Ontario Society of Artists from 1910 until 1915 and at the AAM in 1906; 1908 to 1912; 1914 - 1915; 1922, and 1925. After her election as a member of the Royal Society of British Artists, her work was exhibited from 1913-1915. The Art Association of Montreal held a memorial show featuring 141 of her paintings in 1925.
- Natalie Luckyj, Helen McNicoll : a Canadian Impressionist. Toronto : Art Gallery of Ontario, 1999.
- Prakash, A.K. (2008). Independent Spirit: Early Canadian Women Artists. Buffalo, New York: Firefly Books. p. 288. ISBN 1554074177.
- Art Gallery of Ontario (1979), Canadians in Paris 1867-1914, p. 43
- Prakash, A.K. (2008). Independent Spirit: Early Canadian Women Artists. Buffalo, New York: Firefly Books. p. 267. ISBN 1554074177.
- "Members since 1880". Royal Canadian Academy of Arts. Retrieved 11 September 2013.
- Tyndall, Joy (1997) Lecture: Rebalancing the picture: a few Canadian women artists 1890s to 1910s", pp. 21-22.
|Wikimedia Commons has media related to Helen McNicoll.|
- Dictionary of Canadian Biography
- Biographical note at Collectionscanada.ca
- Biographical note at Virtualmuseum.ca