Foster first rose to prominence as a hockey player in the Winnipeg Junior Hockey League in the early 1920s. With the Winnipeg Argonauts, and later the University of Manitoba, Foster earned a reputation as "the world's finest goaltender." His team won the Manitoba Junior Provincial Championship in 1925, and he was a two-time winner of the Manitoba Championship, first in 1927 with the Winnipeg Winnipegs and in 1930 with the Elmwood Millionaires.
Foster's early career as a hockey player in the Winnipeg Junior Hockey League established his reputation as "the world's finest goaltender," which was further solidified by his success with the Winnipeg Argonauts and University of Manitoba. His teams achieved significant victories, including winning the Manitoba Junior Provincial Championship in 1925 and two Manitoba Championships (in 1927 and 1930).