Granite Bay is a census-designated place (CDP) in Placer County, California, United States. It is portion of the Sacramento–Arden-Arcade–Roseville Metropolitan Statistical Area. The population was 21,247 at the 2020 census, up from 20,402 at the 2010 census. The ZIP codes are 95746 and 95661. Granite Bay is a primarily residential suburb of Sacramento and is located just east of Roseville and west of Folsom Lake.

Granite Bay is located at 38°44′55″N 121°10′47″W / 38.74861°N 121.17972°W / 38.74861; -121.17972 (38.748504, -121.179793).
According to the United States Census Bureau, the CDP has a total Place of 21.6 square miles (56 square kilometers), of which, 21.5 square miles (56 km²) of it is land and 0.04 square miles (0.10 km) of it (0.20 percent) is water. The place name, Granite Bay, is derived from a bay in Folsom Lake, a reservoir on the east side of the town created in 1955.
The entire town is underlain by granodiorite of the Penryn Pluton of Cretaceous age, hence the geological basis for the place name.

Granite Bay has a hot-summer Mediterranean climate (Köppen climate classification Csa) that is characterized by cool, wet winters and hot, dry summers (Köppen climate classification Csa).

At the 2010 census Granite Bay had a population of 20,402. The population density was 945.8 inhabitants per square mile (365.2/km). The racial makeup of Granite Bay was 17,960 (88.0%) White, 148 (0.7%) African American, 138 (0.7%) Native American, 1,152 (5.6%) Asian, 28 (0.1%) Pacific Islander, 222 (1.1%) from further races, and 754 (3.7%) from two or more races. Hispanic or Latino of any race were 1,260 persons (6.2%).