Resident Population in St. Johns County, FL was 334.92800 Thous. of Persons in January of 2024, according to the United States Federal Reserve. Historically, Resident Population in St. Johns County, FL reached a record high of 334.92800 in January of 2024 and a record low of 31.03500 in January of 1970. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in St. Johns County, FL - last updated from the United States Federal Reserve on April of 2026.