This is a list of King County bridges designated by the King County Landmarks Commission as Landmark Bridges.
- Miller River Bridge (1922) on Old Cascade Scenic Highway, Skykomish vicinity.
- Norman Bridge (1950) spanning Middle Fork of Snoqualmie River (428th Avenue SE, North Bend vicinity). Designated in 1984.
- Fourteenth Avenue South Bridge (1930), spanning the Duwamish River between the City of Tukwila and the South Park Community in unincorporated King County. Designated in 1996.
- Mount Si Bridge (1904/1955) spanning the Middle Fork of the Snoqualmie River at the base of Mount Si. Designated in 1997.
- Meadowbrook Bridge (1921) spanning the Snoqualmie River at the community of Meadowbrook. Designated in 1997.
- Tolt Bridge (1922) spanning the Snoqualmie River at Tolt Hill Road south of Carnation. Designated in 1997.
- Stossel Bridge (1951) spanning the Snoqualmie River near Carnation Farms north of Carnation. Designated in 1997.
- Raging River Bridge (1915) at SE 68th Street, Fall City, which carried the Sunset Highway across the Raging River below Preston. Designated 1997.
- Baring Bridge (1930), spanning Index Creek at NE Index Creek Road, vacinity of Baring. Designated 1999.
- Foss River Bridge (1951) spanning a tributary to the Skykomish River in northeast King County. This is a warren pony truss, the only extant example of this type left in the county. Designated in 2004.
- Green River Gorge Bridge (1915) spanning the Green River in southeast King County. This is a rare and intact example of the Baltimore Petit deck truss structural design. The Green River Gorge Bridge is the only Baltimore Petit deck truss bridge owned and maintained by King County. Designated in 2004.
- Judd Creek Bridge (1953), on Vashon Island. A concrete hollow-box (box girder) bridge associated with Homer M. Hadley. Designated in 2004.
- Patton Bridge (1950) spanning the Green River in the vicinity of Auburn. A rare and early example of innovative structural design associated with Homer M. Hadley. In 1994 the Patton Bridge was listed in the National Register of Historic Places as part of the Washington State Highway Bridges, 1941-1950 Multiple Property Documentation. Designated in 2004.