Brazoria County is a county in the U.S. state of Texas, located on the Gulf Coast within the Houston–Sugar Land–Baytown metropolitan area. Regionally, parts of the county are within the extreme southernmost fringe of the regions locally known as Southeast Texas. Brazoria County is among a number of counties that are part of the region known as the Texas Coastal Bend. Its county seat is Angleton, and its largest city is Pearland. Brazoria County, like nearby Brazos County, takes its name from the Brazos River. The county also includes what was once Velasco, Texas, which was the first capital of the Republic of Texas. It served as the first settlement area for Anglo-Texas, when the Old Three Hundred immigrated from the United States in 1821. As of the 2010 census, the population of the county is 313,166.

Brazoria County, like nearby Brazos County, takes its name from the Brazos River, which flows through it. Anglo-Texas began in Brazoria County when the first of Stephen F. Austin's authorized 300 American settlers arrived at the mouth of the Brazos River in 1821. Many of the events leading to the Texas Revolution developed in Brazoria County. In 1832, Brazoria was organized as a separate municipal district by the Mexican government, and so became one of Texas original counties at independence in 1836.
 
Stephen F. Austin's original burial place is located at a church cemetery, Gulf Prairie Cemetery, in the town of Jones Creek, Texas, on what was his brother-in-law's "Peach Point Plantation". His remains were exhumed in 1910 and brought to the state capital in Austin. Also, the town of West Columbia served as the first capital of Texas, dating back to prerevolutionary days.

Group of men at work in Brazoria County
Congressman and 2008 Presidential Candidate Ron Paul lives in Brazoria County, in Lake Jackson. Brazoria County resembles both rural and suburban life, as it is part of the Greater Houston area.