The valley measures approximately 126 kilometres (78 mi) in length from Digby and the Annapolis Basin in the west to Wolfville and the Minas Basin in the east, spanning the counties of Digby, Annapolis and Kings.

Some also include the western part of Hants County, including the towns of Hantsport and Windsor even further to the east, but geographically speaking they are part of the Avon River valley.

The steep face of basaltic North Mountain shelters the valley from the adjacent Bay of Fundy and rises over 260 metres (850 ft) in elevation near Lawrencetown. The granitic South Mountain rises to a somewhat higher elevation and shelters the valley from the climate of the Atlantic Ocean approximately 100 kilometres further south on the province’s South Shore.