Haines City is a city in Polk County, Florida, United States. Its population was 26,669 at the 2020 census. It is part of the Lakeland–Winter Haven Metropolitan Statistical Area. As of the 2020 census, Haines City's population was almost half Hispanic, a quarter white, and about a fifth African American.

Haines City was platted in 1884, shortly after the South Florida Railroad reached the area. The city was originally known as Clay Cut, but there was no railroad station. It is said that the inhabitants persuaded the railroad company to build a station by agreeing to rename their city Haines City, to honor a senior railroad official, former Confederate States Army Colonel Henry Haines.

Haines City was originally incorporated under the General Statutes of Florida as the Town of Haines City on February 23, 1914. The first state legislative act affecting it was enacted on May 20, 1919, and, by Chapter 8272, it was reincorporated as the City of Haines City on January 5, 1925, under a Mayor-Council form of government. The present charter was adopted as Chapter 12790 on July 1, 1927, changing the form of government to "Commission-Manager Plan," as amended. The city operates under a commission-manager form of government and provides the following services as authorized by its charter: Public safety (Police and Fire), Streets and Highways, Culture-Recreation, Public Improvements, Sanitation, Planning and Zoning and General and Administrative Services.

The early settlers planted citrus groves, and citrus growing and processing became the main industry of the city.

African Americans first came to Haines City in 1902 and made a community called "Oakland" named after the various oak tree's that were in the area at the time. Its history is commemorated with a historic district and historical marker. Redevelopment efforts seek to reestablish more business activity in the neighborhood.

From 1974 to 1986, Circus World, a theme park created by the Ringling Brothers and Barnum & Bailey Circus, was open just north of Haines City. After Circus World shut down, it was rebranded & reopened as Boardwalk and Baseball. It featured carnival games and theme park styled rides like the Grand Rapids Flume. It closed in 1990, and the site has been redeveloped as a residential and shopping complex named Posner Park.

In recent years, Haines City has seen explosive growth, largely because of its easy access to Orlando and Walt Disney World Resort. New residential areas have been developed on the edges of the city. On high ground in the north of the city, Southern Dunes, a golf and country club with both vacation homes and residential homes, was developed between 1995 and 2005.

In 2004, Haines City experienced three hurricanes. Hurricane Charley passed through the city in August. Hurricane Frances came right on the heels of Charley but mostly just dumped a lot of rain. Hurricane Jeanne soon followed packing a punch not quite as strong as Charley but longer lasting. The city has since recovered.