James Macdonald Barnsley was born in West Flamboro, near Dundas, Ontario. His childhood was marked by tragedy: the death of his father in 1862 and the drowning of his sister when he was ten. In 1875, the family paper mill business burned down, and he and his mother relocated to St. Louis, Missouri to live with family. Barnsley did not excel at school so he enrolled in art classes, studying under Halsey C. Ives and Paul E. Harney at the St. Louis School of Fine Arts.
By late 1882, Barnsley was in Paris where he studied with Luigi Loir and others. He painted On the Seine, Courbevoie (1883) during this time. Over the next few years, his work was shown at the Paris Salon and in other exhibitions, receiving positive reviews. In 1887, he painted in Italy, Scotland and Ireland. Before the end of the decade, Barnsley would be dividing his time between Montreal and New York.
In January of 1892, Barnsley was admitted for the first time to the Verdun Protestant Hospital after exhibiting symptoms of paranoid schizophrenia. He would never paint again.