Greenbriar is an unincorporated community and census-designated place (CDP) in Pinellas County, Florida, United States. The population was 2,502 at the 2010 census.
Greenbriar is located at 28°0′40″N 82°45′9″W / 28.01111°N 82.7525°W (28.0113, -82.7527). It is bordered by the city of Dunedin to the north and west, the city of Clearwater to the east, and by unincorporated Pinellas County land to the south.
According to the United States Census Bureau, the CDP has a total area of 0.62 square miles (1.6 km2), of which 0.58 square miles (1.5 km2) is land and 0.04 square miles (0.1 km2) (5.82%) is water.