San Juan Bautista is a city in San Benito County, in the U.S. state of California. The population was 2,089 as of the 2020 census. San Juan Bautista was founded in 1797 by the Spanish under Fermín de Lasuén, with the establishment of Mission San Juan Bautista. Following the Mexican secularization of 1833, the town was briefly known as San Juan de Castro and eventually incorporated in 1896.