Crosa is a frazione of the comune of Lessona, in the Province of Biella in the Italian region Piedmont, located about northeast of Turin and about northeast of Biella. Until December 31, 2015, it was an autonomous municipality with 354 inhabitants and an area of . From 1 January 2016 Crosa was absorbed by the neighbouring municipality of Lessona.
As an autonomous comune Crosa bordered the following municipalities: Casapinta, Cossato, Lessona, Strona.