Valle de Santiago is a municipality located in the southern portion of the Mexican state of Guanajuato. It serves as the name for the region's largest township and cabecera municipal. The area covers approximately 819.6 square kilometres (316.4 sq mi) within the Bajío region of central Mexico.
The city of Valle de Santiago is situated at an elevation of 1,744 metres (5,722 ft) in the east-central part of the municipality. It is located roughly 90 kilometres (56 mi) south of Guanajuato, which serves as the state capital.