Rengo is a city and commune located in the Zona Central of Chile, situated in the Cachapoal Province of the O'Higgins Region at a distance of 28 km (17 mi) south of the city of Rancagua and 114 km (71 mi) south of the national capital Santiago. It was named after the courageous Toqui Rengo for his particular bravery at the Battle of Lagunillas.

The Libertador General Bernardo O'Higgins Region, often shortened to O'Higgins Region, is one of Chile's 16 first order administrative divisions. It is subdivided into three provinces. It is named in honour of Bernardo O'Higgins Riquelme, one of Chile's founding fathers.