This article deals with the Eastside region of King County, Washington. For other places and things with the name "Eastside," see the disambiguation page.

The Eastside is the collective term for the eastern suburbs of Seattle, Washington. The major communities are Bellevue, Kirkland, Redmond, Issaquah, and Mercer Island. Others include Beaux Arts Village, Bothell, Clyde Hill, Hunts Point, Kenmore, Medina, Newcastle, Renton, Sammamish, Woodinville, and Yarrow Point.

The Eastside is connected to Seattle by the Evergreen Point Floating Bridge from Medina (Washington State Route 520) and the Lacey V. Murrow Memorial Bridge and Third Lake Washington Bridge from Mercer Island (Interstate 90). It is also served by Interstate 405, a loop route of Interstate 5, which runs to the east of Lake Washington from Tukwila to Lynnwood.