Jacksonville Beach is a coastal resort city in Duval County, Florida, United States. The population was 23,830 at the 2020 census. The city is pa…Jacksonville Beach is a coastal resort city in Duval County, Florida, United States. The population was 23,830 at the 2020 census. The city is part of group of communities collectively referred to as the Jacksonville Beaches on the northern half of San Pablo Island. These communities include Mayport, Atlantic Beach, Neptune Beach, and Ponte Vedra Beach. When the city of Jacksonville consolidated with Duval County in 1968, Jacksonville Beach, together with Atlantic Beach, Neptune Beach, and Baldwin, voted to retain their own municipal governments. As a result, citizens of Jacksonville Beach are also eligible to vote in mayoral election for the City of Jacksonville. It is part of the Jacksonville, Florida Metropolitan Statistical Area.