The Commune of Bionaz (French: Commune de Bionaz; Italian: Comune di Bionaz; known during the years 1939–46 as Biona) is a sparsely populated municipality which extends over 143 km² of the Valpelline area of the Aosta Valley region of northwest Italy. The commune lies on the left side of the river Dora Baltea. The population of c. 240 is dispersed among twenty or more small alpine villages and hamlets including Biona itself, which is the main centre and capoluogo. The commune belongs to the Comunità Montana Grand Combin.