Frankfort Square is an unincorporated community and census-designated place (CDP) in Will County, Illinois, United States.

[5] According to the United States Census Bureau, the CDP has a total area of 2.1 square miles (5.4 km2), all land.

It is bordered by Frankfort to the south, Tinley Park to the north and Matteson (in Cook County) to the east.

There were 2,376 housing units at an average density of 1,133.7 per square mile (437.7/km2).

11.8% of all households were made up of individuals, and 1.4% had someone living alone who was 65 years of age or older.