Seguin is a city in and the county seat of Guadalupe County, Texas, United States; as of the 2020 census, its population was 29,433. Its economy is primarily supported by a regional hospital, as well as the Schertz-Seguin Local Government Corporation water-utility, that supplies the surrounding Greater San Antonio areas from nearby aquifers as far as Gonzales County. Several dams in the surrounding area are governed by the main offices of the Guadalupe-Blanco River Authority, headquartered in downtown Seguin.

Guadalupe County is a county located in the U.S. state of Texas. As of the 2020 census, its population was 172,706. The county seat is Seguin. The county was founded in 1846 and is named after Guadalupe River.