Brazos County is a county in the U.S. state of Texas. As of the 2020 census, its population was 233,849. The county seat is Bryan. Along with Brazoria County, the county is named for the Brazos River, which forms its western border. The county was formed in 1841 and organized in 1843.Brazos County is part of the Bryan-College Station Metropolitan Statistical Area, which consists of Bryan, College Station, and smaller cities and towns in Brazos, Burleson, and Robertson counties.