The huge fjord lies between the cities of Stavanger and Haugesund and dominates the central part of the county.

The main part of the fjord is shared between the municipalities of Kvitsøy, Stavanger, Tysvær, Bokn, and Karmøy.

At its longest, the Boknafjord reaches about 96 kilometres (60 mi) into the mainland at the innermost point of the Hylsfjorden.

Other notable branches include the Saudafjorden, Sandsfjorden, Vindafjorden, Hervikfjorden, Førresfjorden, Erfjorden, Jøsenfjorden, Årdalsfjorden, Idsefjorden, Høgsfjorden, Lysefjorden, and Gandsfjorden.

Some of the notable islands include Vestre Bokn, Kvitsøy, Rennesøy, Ombo, Finnøy, Mosterøy, and the Sjernarøyane archipelago.