Bellevue is a city in the Eastside region of King County, Washington, United States, located across Lake Washington from Seattle. It is th…Bellevue is a city in the Eastside region of King County, Washington, United States, located across Lake Washington from Seattle. It is the third-largest city in the Seattle metropolitan area, and the fifth-largest city in Washington. It has variously been characterized as a satellite city, a suburb, a boomburb, or an edge city. The population was 151,854 at the 2020 census. The city's name is derived from the French term belle vue.