Guapiaçu is a municipality in the state of São Paulo, Brazil, with a population, measured in 2020 by the IBGE, of 21,775 and an area of 326 km2. Is located in the north/northwest of the state, 17 km from São José do Rio Preto.
The city name comes from the Tupi language, and means "Big spring (of a river)".
The settlement of the region began at the end of the 19th century. At the beginning of the 20th century, the city was a village named Ribeirão Claro. On 28 November 1927 the village was elevated to a district. The name changed to its current form in 1945. The city was established as a municipality on 30 November 1953, when it was separated from Rio Preto.
