Greenbriar is an unincorporated community and census-designated place (CDP) in Pinellas County, Florida, United States. As of the 2020 census, Greenbriar had a population of 2,696.
Greenbriar 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 , of which is land and (5.82%) is water.