Fort Pierce is a city in and the county seat of St. Lucie County, Florida, United States. The city is part of the Treasure Coast region of Atlantic Coast Florida. It is also known as the Sunrise City, sister to San Francisco, California, the Sunset City. The population was 41,590 at the 2010 census. As of 2019, the population recorded by the U.S. Census Bureau was 46,103.