After travelling through Europe and the Middle East in 1898–1899, Challener began working as a muralist in earnest and participated in commissions such as the decoration of the recently completed Toronto City Hall.

It became the Canadian Society of Applied Art in 1905, and combined with a City Beautiful movement to encourage murals in civic and commercial establishments.

[7] In Toronto, the Society of Mural Decorators was founded in 1897 by Reid, Challener, William Cruikshank and Edmund Wyly Grier.

The Montreal Gazette wrote of Challener on April 19 of that year that his work entitles him to a place among the foremost of Canadian artists since it is, in the main, "serious and sincere".

The model for the man in the mirror was Challener's close friend of his early years, Walter Allward, playing his cello.

In reviews published in 1900, the Ottawa Citizen wrote that the picture, "showing a young lady, clad in a yellow gown, standing before a piano, expressed, gracefully, an abundance of sentiment",[17] while the Ottawa Evening Journal wrote that the painting was "fresh, daring, and finished" and called Challener "one of Canada’s most promising and original artists.

[19] He received the bronze medal at the Pan American Exhibition for his painting The Workers of the Fields which he deposited in the Royal Canadian Academy diploma collection in the National Gallery of Canada.

[5] His painting Canada's Grand Armada depicts the first contingent of the Canadian Expeditionary Force sailing from the Gaspé in Quebec to Britain in 1914.