Sunnyslope is an unincorporated community and census-designated place (CDP) in Chelan County, Washington, United States. It is part of the Wenatchee–East Wenatchee Metropolitan Statistical Area. The population was 4,041 at the 2020 census, up from 3,252 at the 2010 census.

Chelan County is a county in the U.S. state of Washington. As of the 2020 census, its population was 79,074. The county seat and largest city is Wenatchee. The county was created out of Okanogan and Kittitas Counties on March 13, 1899. It derives its name from a Chelan Indian word meaning "deep water," likely a reference to 55-mile (89 km)-long Lake Chelan, which reaches a maximum depth of 1,486 feet (453 m).