Valle Mosso was a comune (municipality) in the Province of Biella in the Italian region Piedmont, located about 75 kilometres (47 mi) northeast of Turin, 85 kilometres (53 mi) northwest of Milan and 9 kilometres (6 mi) northeast of Biella. As of 31 December 2004 it had a population of 3,965 and an area of 8.9 square kilometres (3.4 sq mi).

Valle Mosso bordered the following municipalities: Bioglio, Campiglia Cervo, Mosso, Pettinengo, Piedicavallo, Strona, Trivero, Vallanzengo, Valle San Nicolao, Veglio.

As a comune it had the following frazioni: Campore, Crocemosso, Falcero, Frignocca, Gallo, Orcurto, Ormezzano, Piana, Picco, Prelle, Premarcia, Simone, Torello

From 1 January 2019 Valle Mosso was absorbed by the new-born municipality of Valdilana.