It was named for Robert Mable, who in 1843 bought 300 acres (about 120 hectares or 1.2 km²) of land on September 11. The Southern Railway opened a railroad station in Mableton in December 1881, and in 1882 the post office opened on June 28, replacing the Bryantville post office about two miles (3 km) southeast. In 1912 it was incorporated as a town on August 19, but in 1916 disincorporated on August 17. The historic original Mable House and plantation, located on Floyd Road just north of Clay Road, now includes an amphitheatre which hosts public events.
There were 10,894 households out of which 34.9% had children under the age of 18 living with them, 53.5% were married couples living together, 14.5% had a female householder with no husband present, and 26.9% were non-families. 21.2% of all households were made up of individuals and 6.7% had someone living alone who was 65 years of age or older. The average household size was 2.72 and the average family size was 3.12.
In the CDP the population was spread out with 26.0% under the age of 18, 8.4% from 18 to 24, 34.4% from 25 to 44, 21.2% from 45 to 64, and 9.9% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 95.9 males. For every 100 females age 18 and over, there were 93.2 males.
The median income for a household in the CDP was $49,426, and the median income for a family was $55,673. Males had a median income of $36,586 versus $31,391 for females. The per capita income for the CDP was $20,814. About 5.9% of families and 8.6% of the population were below the poverty line, including 9.7% of those under age 18 and 9.5% of those age 65 or over.