Sheppard was born in Toronto, and received his art training at the Central Ontario School of Art and Design and the Ontario College of Art under George Reid, John William Beatty, and William Cruickshank.

During his studies he was awarded the Sir Edmund Walker Scholarship in 1912 to 1913, the Stone Scholarship in 1913 to 1914, as well as nine honours diplomas for painting, drawing, and composition.

Earlier in his youth Sheppard served apprenticeships in Toronto commercial engraving houses, and his superb skills as a lithographer provided him with the means of a livelihood throughout his life.

Sheppard was elected a member of the Ontario Society of Artists in 1918 and an Associate of the Royal Canadian Academy in 1929, and his paintings were included in numerous exhibitions, notably the British Empire Exhibition at Wembley in 1925, L’Exposition d’Art Canadien in Paris in 1927, and the World’s Fair in New York in 1939.