Born in Toronto in 1869, James William Beatty made his living in his early life as a fireman and was known for his impetuous and fiery character. By 1893 he was studying art at Gailbraith's Academy under F.M. Bell-Smith, then in 1894 at the Central Ontario School of Art and Design. In 1900 he travelled to Paris to attended the Académie Julian. On his return to Toronto in 1901, he was elected to the Ontario Society of Artists and began to teach from his studio. In 1903 Beatty was elected an associate member of the Royal Canadian Academy (he would become a full member in 1913), and in 1904 he became a founding member of the Graphic Arts Club. Around 1907 he was in London, studying at the Chelsea Polytechnic, and in 1908 he travelled through Europe, including France, Holland, Belgium, Italy and Spain, and produced dark, moody paintings influenced by traditional French and Dutch schools, such as the Barbizon School. On his return to Canada, he resumed teaching.

Beatty had early associations with the Group of Seven during a crucial time in Canadian painting. In 1909 he travelled with Lawren Harris to Haliburton in the spring and Memphremagog in the fall - likely the earliest northern sketching trip by a Group member. In 1914 he took a sketching trip to Algonquin Park with J.E.H. MacDonald and A.Y. Jackson. Beatty's work was considered an early influence on Thomson - Beatty likely sketched with Tom Thomson in Algonquin Park and the two artists both had space at the Studio Building in Toronto. It was Beatty that built the cairn to Thomson's memory at Canoe Lake in 1917.

Beatty was excited by the raw northern wilderness, and it changed his work - his palette brightened, and his paintings became more light-filled. He was part of the rise of a sense of nationalist pride in painting uniquely Canadian landscapes, and was considered an important early catalyst on the art scene. On acquiring Beatty's masterpiece canvas The Evening Cloud of the Northland for the National Gallery of Canada, director Eric Brown wrote to C.W. Jeffreys, "Certainly Canada must nationalize her landscape art before it is of any consequence and I look to you and Beatty as the two who will point out the way to the young ones..."

A member of the Arts & Letters Club in Toronto, an important early meeting place for artists, he was elected its president in 1912. That same year he began to teach at the Ontario School of Art. In spring of 1914, Beatty was commissioned by the Canadian Northern Railway to paint in the Rocky Mountains, though few paintings are known from this trip. During World War I, he was commissioned as a war artist and attached to the Canadian Expeditionary Force in 1917, and travelled to Britain and the front lines in France. On return to Canada, he returned to teaching at the Ontario College of Art, and by 1921 he was the College's Acting Principal; he would remain there until 1941.

Beatty exhibited regularly at the annual exhibitions mounted by the Ontario Society of Artists, the Royal Canadian Academy and the Canadian National Exhibition. In 1913 he was in a group show of Canadian artists at the Macdowell Club in New York, and in
1914 was included in the British Empire exhibition in London. In 1922 he held a one man exhibit at the Haliconian Club in Toronto. His work was shown at Toronto galleries such as the Jenkins Gallery, J. Merrit Maloney, Robert Simpson Company and the Fine Art Galleries, T. Eaton Co. Ltd., as well as internationally at the Jeu de Paume, Paris, the 1924 Wembley exhibition in England and the Boston Arts Club. The year after his death in Toronto in 1941, the Art Gallery of Toronto held a joint memorial exhibition for Beatty and Clarence Gagnon.