Tishomingo is located in southern Oklahoma in Johnston County (of which it is the county seat) north of Madill along U.S. Highway 377/SR 99 and SR 78 on the shores of Lake Texoma.

The town is the historic capital of the Chickasaw Nation. The Chickasaw Council House Museum, a log structure built in 1856, and the Old Chickasaw Capitol, a granite building of the Victorian-Gothic style built about 1898 stand today as memorials to times long past. Museum buffs will also enjoy the Bank of Chickasaw National Museum.

Wildlife enthusiasts enjoy nearby 16,000-acre Tishomingo National Wildlife Refuge with its documented 250 species of birds as well as beaver, raccoon and white-tailed deer. In addition, the Tishomingo National Fish Hatchery is one of the world's largest warm-water hatcheries.

The population estimate for July 1, 1998 was 3,033, a decrease of 83 since 1990.