Harbor Beach is a small city located on Lake Huron in Michigan's Upper Thumb Region, which in turn is a subregion of the Flint/Tri-Cities region.

According to the United States Census Bureau, the city has a total area of 2.09 square miles, of which 1.75 square miles is land and 0.34 square miles is water.

The world's largest man-made fresh water harbor offers a harbor of refuge to ships traveling between Port Huron and Pointe Aux Barques.