Mack is a census-designated place (CDP) in Green and Miami townships, Hamilton County, Ohio, United States.

Its neighbors are Bridgetown to the east, Covedale to the southeast, Delhi Township to the south, Addyston to the southwest, and North Bend and Miami Heights to the west.

According to the United States Census Bureau, the CDP has a total area of 9.3 square miles (24.0 km2), all land.

[9][10][11] Public Library of Cincinnati and Hamilton County operates the Green Township Branch in Mack.

[11][12] The branch, which opened in January 1990, has a central copper dome with two smaller domed structures, which were designed to resemble the barns of horse farms which at one time were prevalent in Green Township.