Rosenberg is a city in the U.S. state of Texas, within the Houston–The Woodlands–Sugar Land metropolitan area and Fort Bend County. It was named for Henry Von Rosenberg, who immigrated to Texas from Switzerland in 1843. Von Rosenberg was an important figure in the settlement of Fort Bend County and the Gulf Coast region. The population was 38,282 at the 2020 census, up from 30,618 at the 2010 census. The community holds the Fort Bend County fair in October. Rosenberg is adjacent to the city of Richmond, the Fort Bend county seat.