Born in Montreal, Mathews first published drawings in the satirical paper, Grip in 1892. After a period working in New York he joined The Montreal Star as a reportage artist, making his reputation in the Montreal art community with portraits of visiting celebrities.
He moved to London in 1907, continuing to send work to the Star whilst increasingly contributing to leading London illustrated magazines, The Graphic and The Bystander, and exhibiting his celebrity portraits, publishing a number as etchings. In later years, he recorded Canadian soldiers during the First World War and moved from portraiture to landscape and architectural subjects. From 1935 he contributed scenes of London life to The Tatler.