Brazoria County is a county in the U.S. state of Texas. As of the 2020 census, the population of the county was 372,031. The county seat is Angleton. Brazoria County is included in the Houston-The Woodlands-Sugar Land metropolitan statistical area. It is located in the Gulf Coast region of Texas. Regionally, parts of the county are within the extreme southernmost fringe of the regions locally known as Southeast Texas.