Westwood is a census-designated place (CDP) in Lassen County, California, United States. Westwood is located 20 miles (32 km) west-southwest of Susanville, at an elevation of 5,128 feet (1,563 m). The population was 1,647 at the 2010 census, down from 1,998 at the 2000 census.
Westwood is built upon lava flows from Cascade Mountain Range volcanoes to the north. Keddie Ridge is considered to be at the northern end of the Sierra Nevada Mountain Range.
According to the United States Census Bureau, the CDP has a total area of 5.5 square miles (14 km2), of which 5.4 square miles (14 km2) is land and 0.1 square miles (0.26 km2) (1.34%) is water.