Colchagua Province is one of three provinces of the central Chilean region of O'Higgins (VI). Its capital is San Fernando. It is bordered on the north by Cachapoal Province, on the east by the Argentine Republic, on the south by Curicó Province, and on the west by Cardenal Caro Province.

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.