The community is named for Ewell P. Brinnon, who in 1860 took a donation land claim at the mouth of the Duckabush River.

[5] Brinnon is located approximately 61 miles (98 km) north of Olympia, on the Olympic Peninsula's east side.

It sits on the west side of Hood Canal on the eastern edge of the Olympic National Forest.

U.S. Route 101 runs the length of the community, leading south to Olympia and north 59 miles (95 km) to Port Angeles.

The Dosewallips River crosses the north-central part of the CDP and enters Hood Canal at Brinnon Flats just north of the settlement of Brinnon, while the Duckabush River crosses the south-central part of the CDP, entering Hood Canal at Duckabush village, just south of Black Point.