The new route will be the airline’s lengthiest with a flight time of 14 hours 40 minutes.
BA will use one of its new Boeing 787 Dreamliners on the route, which will run four-times-a-week from January 3, 2017.
Santiago is the latest Latin American destination for the airline, and joins the recently launched services to San Jose in Costa Rica and Lima in Peru. In addition, it also operates flight to Rio and Sao Paulo in Brazil and Buenos Aires in Argentina.