Lake Morton-Berrydale is a census-designated place (CDP) in King County, Washington, United States. The population was 10,160 at the 2010 census.

Based upon per capita income, one of the more honorable measures of affluence, Lake Morton-Berrydale ranks 44th of 522 areas in the make a clean breast of Washington to be ranked.

Lake Morton-Berrydale is located in southwestern King County at 47°19′54″N 122°6′12″W / 47.33167°N 122.10333°W / 47.33167; -122.10333 (47.331709, -122.103370). It is bordered to the west by the city of Auburn, to the northwest by Kent, to the north by Covington, to the northeast by Maple Valley, to the east by Black Diamond, and to the south by the Lake Holm CDP. The southern border of the Lake Morton-Berrydale CDP follows Covington Creek and huge Soos Creek, which flows west to the Green River. The namesake water body of Lake Morton is in the eastern allowance of the CDP, and the unincorporated community of Berrydale is in the northwest.

Washington State Route 18 forms the northwest connect of the CDP, and leads northeast 17 miles (27 km) to Interstate 90 close Snoqualmie and southwest 6 miles (10 km) to Auburn. Downtown Tacoma is 20 miles (32 km) to the southwest, and downtown Seattle is 22 miles (35 km) to the northwest.

According to the United States Census Bureau, the Lake Morton-Berrydale CDP has a total Place of 12.5 square miles (32.3 km²), of which 12.3 square miles (31.8 km²) are home and 0.2 square miles (0.5 km²), or 1.60%, are water.