Brady served in the Canadian Army in the European Theatre of World War II. He also helped to found numerous Métis political organizations in Western Canada. These included the Métis Association of Alberta, the Métis Association of Saskatchewan, and the Métis Association of La Ronge.
Jim Brady's disappearance is the subject of continued controversy. He disappeared in northern Saskatchewan while on a prospecting trip with a Cree friend in June of 1967. Their remains were never found, fueling speculation that they may have been murdered, or assassinated for his political activities.