Born in Halifax, Nova Scotia, Canada, Foster moved to the United States in 1921, and began his illustration career in Chicago, eventually becoming an American citizen.

He later moved there in 1921, and began working for the Jahn & Ollier Engraving Co.[4] Foster freely "audited" classes at the Chicago Academy of Fine Arts, a practice commonly made back then by poor students, which is confirmed by the fact that the Art Institute has no record of him taking formal classes.

[5] In 1925, Foster began working for the Chicago advertising studio Palenske-Young, Inc., and his clients were: Union Pacific Railroad, Johnson Outboard Motors, Wurlitzer Grand Pianos, Jelke Margarine, and the International Truck Company.

In 1928, Palenske-Young was hired by Joseph Henry “Joe” Neebe, owner of Famous Books and Plays, to adapt the novel Tarzan by Edgar Rice Burroughs into a 10-week comic strip series.

Prolonged anesthesia during a hip replacement surgery in November 1979 took his memory, and he no longer remembered ever doing Tarzan or Prince Valiant.

Harvey argues that Foster and Flash Gordon artist Alex Raymond "created the visual standard by which all such comic strips would henceforth be measured.

"[12] Foster's clear yet detailed panels, uncluttered by word balloons, were appreciated by contemporaries of his generation such as Lynd Ward,[13] but perhaps his greatest impact was on the young artists who drove the Golden Age of Comics.

[19] Frank Frazetta called Foster's work on Tarzan "perfection, a landmark in American twentieth-century art that will never be surpassed.

"[20] Among the many other artists who have cited Foster as an important influence are Carl Barks,[21] Steve Ditko,[22] Mark Schultz,[23] William Stout,[24] Bill Ward,[25] and Al Williamson.

A rare honor came in 1965, when Foster was made a Fellow of the Royal Society of Arts (FRSA) in London, a first for any American cartoonist.