In 1826, the county established its seat in the settlement of Bullsboro with Walter Colquitt as the first superior-court judge. The scarcity of defined roads led to the settlement, a new site was located roughly two miles west. The county seat was named Newnan after the North Carolina Native, General Daniel Newnan, who was a soldier and later became Georgia Secretary of State and a United States Congressman. Lawyers, doctors, and merchants began conducting busi­ness once Newman was established as a town. The city was laid out in a grid pattern with a nine block central business district, the center of which was the court­house.

Due in part to the success of the cotton industry, Newnan prospered at the turn of the centu­ry. Newnan’s leading citizens invested in the railroad during the mid l800’s. This brought economic prosperity to the town and estab­lished Newnan as one of the wealthiest towns per capita in the United States. The passenger railroad line to Newnan was opened in 1851. The streets were named for such famous Americans as Jackson, Jefferson, Washington and Madison. Ultimately, Newman became the main economic center for the county. The county had grown to almost 15,000 people by 1860 and was evenly divided between whites and blacks, with plantations and farms the main means of income.

The Battle of Brown's Mill was fought outside Newnan in 1864 and due to its location on the Atlanta and West Point Railroad, and its distance from the heaviest battles, the largest town in Coweta was selected to host a hospital for treating the wounded. Eventually Newnan would have seven hospitals and treat more than 10,000 soldiers from both sides. Many soldiers, including 269 Confederates who died in the town's hospitals, were buried in nearby Oak Hill Cemetery. After the war the southern economy changed. The textile industry found its way to the South and Coweta County. In 1866 the Willcoxon Manufacturing Company was the first cotton plant built in the county.

By the early 1900s more cotton factories had opened. Textile mills continued to be built in the county. Together with such manufacturing firms as R. D. Cole, builder of Newnan's first water tower and manufacturer of war supplies, they made the county quite prosperous. Today Coweta County encompasses 443 square miles in west central Georgia, bordered by Carroll, Fayette, Fulton, Heard, Meriwether, and Troup counties. Some prominent natives of Coweta County include New York classical musician and conductor Charles Wadsworth, Pulitzer Prize–winning journalist Buford Boone, country singers Alan Jackson and Doug Stone, writers Lewis Grizzard and Erskine Caldwell, and former Georgia governors Ellis Arnall and William Y. Atkinson.