Union Hill-Novelty Hill is a census-designated place (CDP) in King County, Washington, United States.

[citation needed] Union Hill-Novelty Hill is located in northern King County and is bordered to the west by the city of Redmond, and a separate portion of the city, comprising the Redmond Watershed Preserve, is surrounded by the northern part of the CDP.

To the north is the Cottage Lake CDP, and Washington State Route 202 runs along the southern edge of the community in the valley of Evans Creek and Patterson Creek.

The Ames Lake CDP is to the southeast, and downtown Seattle is 20 miles (32 km) to the southwest.

9.0% of all households were made up of individuals, and 2.0% had someone living alone who was 65 years of age or older.