The Valchiavenna (Italian: [valkjaˈvɛnna]; Lombard: Valciàvena [ʋaltʃaˈʋɛna]) is an alpine valley in the province of Sondrio, in Lombardy in northern Italy. It lies to the north of Lake Como, and is traversed by the rivers Mera and Liro. It can be divided into three parts which branch from the confluence of these rivers near Chiavenna, the principal town of the region.

The lower part, the Bassa Valchiavenna, follows the course of the Mera downstream through the Piano di Chiavenna to Lago di Mezzola, and continues across the Pian di Spagna to the Trivio di Fuentes near Colico. Its territitory lies within the comuni of Mese, Prata Camportaccio, Gordona, Samolaco, Novate Mezzola and Verceia.

The northern part consists of the Valle Spluga, the valley of the Liro river which leads up to the Splügen Pass on the border with Switzerland and includes the comuni of San Giacomo Filippo, Madesimo, and Campodolcino.