Kissimmee (/kɪˈsɪmi/ ⓘ kih-SIM-ee) is the largest city and county seat of Osceola County, Florida, United States. As of the 2020 census, the population was 79,226. It is a Principal City of the Orlando-Kissimmee-Sanford, Florida, Metropolitan Statistical Area, which had a 2020 population of 2,673,376. The Census Bureau defines an urban area with Kissimmee as the principal city, which is separated from the Orlando urban area. The Kissimmee–St. Cloud, FL urban area had a 2020 population of 418,404, making it the 100th largest in the United States.

The area was originally named Allendale, after Confederate Major J. H. Allen, who operated the first cargo steamboat along the Kissimmee River—the Mary Belle. It was renamed Kissimmee when incorporated as a city in 1883. The modern town, the county seat of Osceola County, was founded before the Civil War by the Bass, Johnson and Overstreet families. The etymology of the name Kissimmee is debated, apart from general agreement that it is Native American in origin. Its growth can be credited to Hamilton Disston of Philadelphia, who based his four-million acre (8,000 km2) drainage operation out of the town. Disston had contracted with the financially wobbly state of Florida to drain its southern lands, for which he would own half of all he successfully drained. This deal made Disston the largest single landowner in the United States.

Disston's dredging and land speculation required a small steamboat industry to transport people and goods along the new waterway. The Kissimmee shipyard was responsible for building most of these large steamships, which were just one jump ahead of civilization—with Kissimmee as the jumping off point. Concurrently, the South Florida Railroad was growing and extended the end of its line from Sanford down to Kissimmee, making the town on Lake Tohopekaliga a transportation hub for Central Florida. On February 12, 1885, the Florida Legislature incorporated the Kissimmee City Street Railway.

But Kissimmee's heyday was short-lived. Expanding railroads began to challenge the steamships for carrying freight and passengers. By 1884, the South Florida Railroad, now part of the Plant System, had extended its tracks to Tampa. The Panic of 1893 was the worst depression the U.S. had experienced up to that time, crushing land speculation and unsound debt. Disston closed his Kissimmee land operation. Consecutive freezes in 1894 and 1895 wiped out the citrus industry. The freezes, combined with South Florida's growth and the relocation of steamship operations to Lake Okeechobee, left Kissimmee dependent on open range cattle ranching.

Kissimmee had a population of 4,310 in 1950. At that point, there was some citrus packing as well as ranching.

Ranching remained an important part of the local economy until Walt Disney World opened nearby in 1971. After that, tourism and development supplanted cattle ranching to a large measure. But even though the Disney facility took over much of the open range cattle lands, cattle ranches still operate nearby, particularly in southern Osceola County.

The 1998 Kissimmee tornado outbreak killed dozens of people in the area. On August 13, 2004, Hurricane Charley passed through Kissimmee with winds in excess of 100 miles per hour (160 km/h), damaging homes and buildings, toppling trees and cutting electrical power to the entire city. Kissimmee Utility Authority restored power to 54 percent of the residents in the first 72 hours and to 85 percent within one week. Service was restored to all customers on August 28. Three weeks after Hurricane Charley, the area was struck by Hurricane Frances, then Hurricane Jeanne three weeks later.

According to the United States Census Bureau, the city has an area of 17.32 square miles (44.9 km2), of which 16.7 square miles (43 km2) is land and 0.6 square miles (2 km2), comprising 3.7%, is water. Kissimmee and St. Cloud are the county's only incorporated settlements. They are in proximity to each other along U.S. Highways 192 and 441.

A large geographical area of unincorporated Osceola County is also referred to as Kissimmee. This includes most of the 192 corridor west of the city border to Highway 27, areas north of the city to Hunters Creek, and areas south of the city to Poinciana.

The city is mostly built on deep sand which is poorly drained in its natural state. The most common soil series is Myakka.

Drained by the Kissimmee River, the city is on the northwest shore of Lake Tohopekaliga (locally called Lake Toho, West Lake Toho, or simply West Lake) in central Florida. Shingle Creek, largely considered the headwaters of the Everglades, also runs through the city, and features a canoe/kayak trail that runs from Steffe Landing on US 192 and ends in Lake Tohopekaliga.

The downtown area lies near the intersection of U.S. Highway 17/92 and U.S. Highway 192. Downtown Kissimmee has no skyscrapers; most of the buildings are two or three stories high. The biggest and the tallest building downtown is the Osceola County courthouse. The main thoroughfare follows Highway 17/Highway 92 through the city's center and is a combination of three streets: Main Street, Broadway Street, and Emmett Street. The downtown area consists largely of restaurants, small shops, and historic residences. The University of Central Florida has a business incubator in the area that is an important part of the economic engine downtown.

The climate in this area is characterized by hot, humid summers and generally mild, dry, and sunny winters. According to the Köppen climate classification system, Kissimmee has a humid subtropical climate (Cfa).

As of the 2020 United States census, there were 79,226 people, 22,836 households, and 15,732 families residing in the city.

As of the 2010 United States census, there were 59,682 people, 22,040 households, and 15,812 families residing in the city.

Out of Kissimmee's 58.93% Hispanic or Latino residents in the 2010 US census, 33.1% were Puerto Rican, 5.1% Dominican, 4.0% Colombian, 3.9% Mexican, 2.6% Cuban, 1.4% Venezuelan, 0.9% Ecuadorian, 0.7% Salvadoran, 0.7% Peruvian, 0.6% Honduran, and 0.6% were Nicaraguan. Also in 2010, out of the 9.59% non-Hispanic African American or Black residents, there was an additional 2.8% of people who were Afro-Latino or Black Hispanic. The 2010 census also showed that from the 3.23% Asians living in Kissimmee, 1.1% were Indian and 0.8% were Filipino.

As of the 2000 census, there were 47,814 people, 17,121 households, and 11,813 families residing in the city. The population density was 2,866.6 inhabitants per square mile (1,106.8/km2). There were 19,642 housing units at an average density of 1,177.6 per square mile (454.7/km2). The racial makeup of the city was 67.22% White, 9.99% African American, 0.52% Native American, 3.38% Asian, 0.10% Pacific Islander, 14.15% from other races, and 4.66% from two or more races. Hispanic or Latino people of any race were 41.73% of the population. The majority of Hispanics residing in the city are Puerto Ricans. There are also small Colombian, Cuban and Dominican communities residing in and/or around the city.

In 2000, there were 17,121 households, out of which 37.4% had children under the age of 18 living with them, 47.2% were married couples living together, 15.8% had a female householder with no husband present, and 31.0% were non-families. 20.9% of all households were made up of individuals, and 4.9% had someone living alone who was 65 years of age or older. The average household size was 2.77 and the average family size was 3.21.

In 2000, in the city, the population was spread out, with 27.0% under the age of 18, 12.0% from 18 to 24, 34.9% from 25 to 44, 18.5% from 45 to 64, and 7.6% who were 65 years of age or older. The median age was 31 years. For every 100 females, there were 98.1 males. For every 100 females age 18 and over, there were 95.8 males.

As of 2000, the median income for a household in the city was $33,949, and the median income for a family was $36,361. Males had a median income of $25,851 versus $21,025 for females. The per capita income for the city was $15,071. About 12.3% of families and 15.4% of the population were below the poverty line, including 19.0% of those under age 18 and 10.2% of those age 65 or over.

Multinational multi-level marketing company Tupperware Brands is based in Kissimmee.

According to Kissimmee's 2023 Annual Comprehensive Financial Report, the city's top employers are:

From 1985 to 2016, the Houston Astros conducted spring training in Kissimmee, at Osceola County Stadium. The stadium also hosts numerous amateur baseball events throughout the year in conjunction with USSSA, Triple Crown Sports, World Baseball Federation and Promotion Sports. The Jim Evans Academy of Professional Umpiring has also called Osceola County Stadium home since 1994.

Austin-Tindall Regional Park is an athletic facility in the area that hosts a variety of annual events.

The city is also home to the annual NCCAA men's soccer National Championship Tournament.

Osceola Heritage Park is an event facility featuring a concert arena (Silver Spurs Arena) and professional sports stadium (Osceola County Stadium). The Silver Spurs Arena has hosted many acts, from Hilary Duff and Bob Dylan to an annual rodeo. Jehovah's Witnesses use Silver Spurs Arena for their annual district conventions. In 2008, a number of English and Spanish conventions were held by the Witnesses, bringing thousands of delegates to the Kissimmee area for the three-day events.

Kissimmee has a number of public parks, including:

The Shingle Creek Regional Trail (SCRT) is an inter-governmental project that is planned to connect Kissimmee to Orlando through a 32-mile bicycle trail. It runs along the environmentally sensitive Shingle Creek, and was included on President Obama's America's Great Outdoors list.

Kissimmee is home to a number of golf courses and mini-golf courses.

Kissimmee is near Orlando, home to Universal Orlando Resort and SeaWorld Orlando, and Lake Buena Vista/Bay Lake, home to Walt Disney World Resort, allowing tourists to access the parks through the city.

The School District of Osceola County serves Kissimmee. High schools include:

Kissimmee features a multi-modal transportation hub between Neptune Road and Monument Street. It includes the Amtrak train station, which is a stop on the SunRail commuter rail system. There is a Greyhound bus station. The hub also has a bus terminal providing service by the Lynx network.

Kissimmee Gateway Airport has four fixed-base operators that provide service to the area. Kissimmee Gateway Airport (ISM) accommodates general aviation air service 24 hours a day with two paved airport runways—respectively 5,000 and 6,000 feet (1,500 and 1,800 m). There are also two flight training schools and a museum at the airport. Orlando International Airport can be reached from Kissimmee in 40 minutes by car.

The major roads in the Kissimmee area are Florida's Turnpike, Interstate 4, Osceola Parkway, and US 192. Among other important routes are US 17/92 that join with US 441 into the Orange Blossom Trail (OBT) and the John Young Parkway.

The city of Kissimmee also runs a service named Freebee Kissimmee which is a cab that provides transportation around Downtown Kissimmee, Advent Health, and Valencia College.

Osceola Library System operates the Hart Memorial Central Library in Kissimmee.