Pearl Beach is an unincorporated community and census-designated place (CDP) in St. Clair County in the U.S. state of Michigan. The population of the CDP was 4,698 at the 2020 census. The community is located within Clay Township.

St. Clair County is a county located in the U.S. state of Michigan and bordering the west bank of the St. Clair River. As of the 2020 census, the population was 160,383. It is the 13th-most populous county in the state. The county seat is Port Huron, located at the north end of the St. Clair River at Lake Huron. The county was created September 10, 1820, and its government was organized in 1821. It is located northeast of Detroit. It is considered by the State of Michigan to be a part of The Thumb, a peninsula that is surrounded by Lake Huron in the east-central area of the state. This area is sometimes dubbed the Blue Water Area.