Tullahoma is a city in Coffee and Franklin counties in southern Middle Tennessee, United States. The population was 20,339 at the 2020 census. In 2019, the population was estimated to be 19,555. It is the principal city of the Tullahoma micropolitan area (a 2009 estimate placed it at 99,927), which consists of Coffee and Moore counties and is the second largest micropolitan area in Tennessee. The city is also partially in the Winchester Micropolitan area.

Tullahoma was founded in 1852 as a work camp along the new Nashville and Chattanooga Railroad. Its name is derived from the Choctaw phrase tʋli homma, meaning "red rock". An alternative explanation (see Sam Davis Elliott's Soldier of Tennessee and sources cited therein) of the name is that Peter Decherd, who donated the land for the railroad right-of-way (and was therefore given the right to name two stations along the line), named one station Decherd, after himself, and the other as Tulkahoma (later changed to Tullahoma). Tullahoma was the name of Decherd's favorite horse, which had been named for a Choctaw chief captured by Decherd's grandfather. (There was also a town called Tullahoma in Mississippi, which later changed its name to Grenada.)

The earliest settlement was by farmers from Virginia and North Carolina. Using African-American slave labor, they developed plantations for tobacco and hemp. Slaves also tended their livestock, both horses and cattle. Early families were named Moore, Decherd (pronounced as Deckerd), Anderson, Ragon, Montgomery, Ferrell, Stephenson, and Gunn.

They called a nearby spring Bottle Spring, though it was later known as John Gunn's Spring, since it was on his property. Nowadays, it is called Big Springs. This spring provided water for the steam locomotives. Later it was exploited for health and tourist attractions, as the town developed spa facilities.

When the Civil War began in April 1861, Company B, 1st Regiment of Tennessee Volunteers, was formed in Tullahoma. It joined General Robert E. Lee's Army of Northern Virginia. The division fought in the battles of Bull Run, Fredericksburg, Chancellorsville, Gettysburg, and Petersburg, before surrendering to Union General Ulysses S. Grant at Appomattox.

During the war, Tullahoma served in 1863 as the headquarters for the Confederate Army of Tennessee. That year the Union Army undertook the Tullahoma Campaign, defeating Confederate forces and taking control of Middle Tennessee. Federal troops occupied this area for the duration of the war. As a result of the campaign, Union forces captured Chattanooga.

Tullahoma was little more than a rough frontier outpost, and had no paved streets. 1863 was a wet year, and the place became known to the bedraggled troops of both sides as a place of endless mud. An aide on Confederate General William Hardee's staff is said to have written his own account of the origin of the name: "It is from two Greek words – 'Tulla' meaning mud, and 'Homa,' meaning more mud."

The selection of Tullahoma as a headquarters by Confederate General Braxton Bragg has been much criticized by military historians. Although the location was strategic with regard to the road and rail network, it had no strong natural defenses. Bragg did little to fortify it while his forces occupied the area. Eventually the town was evacuated without a battle.