Shiner was elected to the North York Board of Control in 1976, and remained a member until her death. The position gave her an automatic seat on the Metropolitan Toronto Council. She served on Metro's transportation committee for several years, and was a frequent rival to fellow councillor Anne Johnston. She was also appointed to the management board of the O'Keefe Centre for the Performing Arts in 1979, and remained a board member until 1986. Shiner supported the principle of amalgamation for Toronto's six municipal governments in 1978, on the grounds that it would yield a better transportation system.