Keystone Heights is a city located in southwestern Clay County, Florida, United States.

It is the southwestern most city in the Jacksonville, Florida Metropolitan Statistical Area, and is the principal city and primary economic driver of the Lake Region, a region in Florida consisting of southwestern Clay County and parts of Bradford, Putnam, and Alachua counties, known for its many lakes.

In 1917, the area that would eventually become known as the city of Keystone Heights was a small community known as "Brooklyn" located along present day State Road 100, about one mile north of the present location of Keystone Heights on Lake Brooklyn.

Property Developer John J. Lawrence, who hailed from Pennsylvania, noticed the area on a visit to Lake Brooklyn, and instantly became attracted to the region.

After hearing of natural wonders and the many different lakes of the area, other families moved to Keystone, putting a strain on those attempting to build structures within the city.

Helping to address the issue, in late 1921, C. Ray Lawrence came to Keystone Heights, and began laying out the streets and lots in the city.

[1] The opening of the Keystone Inn on New Year's Day in 1923 was one of the most significant events in the early history of the city.

The inn burned down in October 1954 and was never rebuilt, and the property on which it formerly stood is now a park in front of City Hall.

[1] In 1984, an American sycamore seedling, germinated by the United States Forest Service, was planted at the Keystone Heights Library.

The "Moon Tree" traveled with Stuart Roosa, a former U.S. Forest Service smokejumper, aboard the Apollo 14 mission on January 31, 1971.

Roosa and his five varieties of seeds orbited the Moon 34 times and the resulting seedlings were planted all around the United States and the world.

[7] In the early 2000s, the city saw its tourism industry decline as many of its surrounding lakes, which serve as a primary inflow point for the Floridan aquifer, nearly disappeared.

In April 2022, Keystone Beach hosted the Motosurf Games, a motorized surfboard racing contest on Lake Geneva that was televised on CBS Sports.

[11] The approximate coordinates for the City of Keystone Heights is located in Northeast Florida in the southwest corner of Clay County, at 29°47′14″N 82°1′59″W / 29.78722°N 82.03306°W / 29.78722; -82.03306 (29.787243, –82.033026).

[19] In 2020, the ten largest ancestry groups in the city were German (14.4%), Irish (9.9%), English (7.2%), American (4.7%), Italian (4.6%), Polish (2.7%), Dutch (2.4%), Russian (1.5%), Welsh (1.4%), and European (1.3%).