Kitsap County is essentially the same as the Kitsap Peninsula, the large peninsula bounded by Hood Canal on the west and Admiralty Inlet on the east. There is a large concentration of military installations in the county, the largest being the Puget Sound Naval Shipyard in Bremerton.

The county seat is Port Orchard, across the bay from Bremerton. The northern parts of the county, including Silverdale and Poulsbo, have grown rapidly, particularly since the construction of the Hood Canal Bridge simplified their connection to the Olympic National Park. The county also include Bainbridge Island.