Georgian Bay (French: Baie Georgienne) is a large bay of Lake Huron, located entirely within Ontario, Canada. The main body of the bay lies east of the Bruce Peninsula and Manitoulin Island. To its northwest is the North Channel.

Georgian Bay is surrounded by (listed clockwise) the districts of Manitoulin, Sudbury, Parry Sound and Muskoka, as well as the more populous counties of Simcoe, Grey and Bruce. The Main Channel separates the Bruce Peninsula from Manitoulin Island and connects Georgian Bay to the rest of Lake Huron. The North Channel, located between Manitoulin Island and the Sudbury District, west of Killarney, was once a popular route for steamships and is now used by a variety of pleasure craft to travel to and from Georgian Bay.