The Willapa Hills is a geologic, physiographic, and geographic region in southwest Washington.

When described as a physiographical province, the Willapa Hills are bounded by the Pacific Ocean to the west, the Columbia River to the south, the Olympic Mountains to the north, and the Cascade Range to the east.

[1] Some definitions place the Puget Lowland physiographic province east of the Willapa Hills.

[2] Included within the province are the Black Hills, the Doty Hills, and a number of broad river valleys, some of which open up into broad estuaries on the Pacific such as Grays Harbor and Willapa Bay.

The Willapa Hills are the lowest uplands in the entire Pacific Coast Range system.