Mapp was born in Social Circle, Walton County, Georgia. He relocated in 1922 to Newton County, where he met the guitar player Curley Weaver. Mapp was noted in Newton County as a harmonica virtuoso with a unique style, who often performed for tips on the street. In 1925 Weaver and Mapp left for Atlanta. The twosome played at country dances. Weaver then formed a group with Mapp, Barbecue Bob, and Bob's brother Charlie Hicks and continued to play locally.
In November 1931, Mapp was found stabbed on an Atlanta street corner. His death certificate recorded that the brachial artery in his left arm had been severed. It gave his age as twenty. No one was charged with his murder. The certificate also noted that he was a musician; it was unusual at the time for a coroner to acknowledge such employment.
A compilation album, Georgia Blues 1928-33, released in 1994 by Document Records (DOCD-5110), provides the most complete discography of Mapp's work. It includes the following pieces featuring Mapp: