Collier County is a county located in the U.S. state of Florida. As of the 2010 census, the population was 321,520. Its county seat is East Naples, where the county offices were moved from Everglades in 1962.Collier County comprises the Naples-Immokalee-Marco Island, FL Metropolitan Statistical Area, which is included in the Cape Coral-Fort Myers-Naples, FL Combined Statistical Area.