Rockwall County is a county in the U.S. state of Texas. At 149 square miles, Rockwall County has the smallest area of any Texas county. Per the 2020 Census, its population was 107,819. Its county seat is Rockwall. The county and city are named for a wall-like subterranean rock formation that runs throughout the county.

Rockwall is a city in Rockwall County, Texas, United States, which is part of the Dallas/Fort Worth metroplex. It is the county seat of Rockwall County. The U.S. Census Bureau estimates that as of the 2020 census, Rockwall's population is 47,251, up from 45,888 in 2019. The name Rockwall is derived from a naturally jointed geological formation, which has the appearance of an artificial wall.