Jefferson County is a county located in the Big Bend region in the northern part of the U.S. state of Florida. As of the 2020 census, the population was 14,510. Its county seat is Monticello.

The Big Bend of Florida, United States, is an informally named geographic region of North Florida where the Florida Panhandle transitions to the Florida Peninsula south and east of Tallahassee. The region is known for its vast woodlands and marshlands and its low population density relative to much of the state. The area is home to the largest single spring in the United States, the Alapaha Rise, and the longest surveyed underwater cave in the United States, the 32-mile (51 km) Wakulla-Leon Sinks cave system.