Jacksonville Beach is a coastal resort city in Duval County, Florida, United States. It was incorporated on May 22, 1907, as Pablo Beach, and changed to Jacksonville Beach in 1925. The city is part of group of communities collectively referred to as the Jacksonville Beaches. 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. As of the 2020 US census, Jacksonville Beach had a total population of 23,830.

Duval County is in the northeastern part of the U.S. state of Florida. As of July 2022, the population was 1,016,536, up from 864,263 in 2010. It is Florida's sixth-most populous county. Its county seat is Jacksonville, with which the Duval County government has been consolidated since 1968. Duval County was established in 1822, and is named for William Pope Duval, Governor of Florida Territory from 1822 to 1834. Duval County is the central county of the Jacksonville Metropolitan Statistical Area.