Haines City is a city in Polk County, Florida, United States. Its population was 13,174 at the 2000 census and 20,535 at the 2010 census. It is the third most populous city in Polk County. It is part of the Lakeland–Winter Haven Metropolitan Statistical Area, which, in turn, is considered part of the Tampa Bay Area.

Haines City is located within the Central Florida Highlands area of the Atlantic coastal plain, part of the Lake Wales Ridge, a sandy terrain consisting of a low ridge of gently rolling hills rising from the coastal flatlands.

According to the United States Census Bureau, the city has a total area of 19.8 square miles (51 km2), of which 8.3 square miles (21 km2) is land and 0.6 square miles (1.6 km2), 7.27% of the total, is water.

Haines City is located in the humid subtropical zone as designated by (Köppen climate classification: Cfa). The porous white sands and open terrain create the often hot and dry climate that parts of interior Florida near the Lakes Wales sand ridge is known for.