It drains the western side of Chile's Cordillera de la Costa and has a total length of 42 kilometres (26 mi).

The Andalién River is formed by the union of the Poñén from the north and the Curapalihue from the south in the commune of Florida.

It then flows southwest and west, and eventually northwest into the city of Concepción, Chile.

After the city of Concepción, it flows north through the former villages (now neighbourhoods) of Andalién and El Rosal, and then the communes of Talcahuano, and Penco.

The Andalién river basin covers approximately 23% of the province of Concepción and also includes part of the municipalities of Penco, Florida, Talcahuano and Tomé.