He was of entirely English ancestry; his first immigrant ancestor was Thomas Lumpkin, who moved from England to Virginia during the colonial period.

He received an appointment by the Georgia governor as the State Indian Commissioner,[2] where he ran boundary lines between the state of Georgia and Creek Indian lands as part of the Treaty of the Creek Agency (1818).

As governor, Lumpkin directed the release of two missionaries, Samuel A. Worcester and Elizur Butler, who had been imprisoned for dwelling in the Cherokee territory and refusing to take an oath of allegiance to Georgia.

Lumpkin was elected to the U.S. Senate to fill the vacancy caused by the resignation of John P. King and served the remainder of his term from November 22, 1837, to March 3, 1841.

He died a few years after the end of the Civil War, in Athens in 1870; interment was in Oconee Hill Cemetery.

He instead asked for his young daughter Martha Atalanta Lumpkin (later Compton), to be the honoree of the city's first true name, "Marthasville."