It then flows in the Tena Valley through the municipalities of Sallent de Gállego, Panticosa and Biescas.

Starting from Sabiñánigo it forms a wide elbow until Triste, from which it continues in its primitive north–south direction until flowing into the Ebro near Zaragoza.

The main tributaries of the Gállego in its upper basin are the Aguas Limpias, Caldarés, Escarra, Lana Mayor and Aurín.

In the medium and lower basin, they include Guarga, Seco, Asabón and Sotón.

This river gives its name to the Alto Gállego comarca of Aragon.