It is included between the Grigne range from West, and the Bergamo Prealps which, in a half-circle stretching from North to East, separate it from the valley of the area of Bergamo and the Valtellina. Valsassina also reaches the Lecco's branch of Lake Como at Lecco itself and Bellano.
The valley is run by the Pioverna stream, which flows from the Grigne to the Lake Como.
