The Corporation of the Municipality of Markstay-Warren is located within the Sudbury East area, between the City of Greater Sudbury and the City of North Bay. It is comprised of Townships of Hagar, Ratter, Dunnet, Awrey and portions of the Townships of Hawley, Street, Loughrin and Henry. The three (3) major centres within the Municipality are the Village of Markstay, the Village of Hagar, and the village of Warren.

On January 1st, 1999, the Municipality of Markstay-Warren amalgamated to include the Towns of Warren, Markstay and the Townships of Awrey, Street, Hawley, Loughrin and Henry.