Born a sharecropper's daughter in Shelby County, Tennessee, Koko boarded a bus to Chicago in 1954 as part of the great migration of southern blacks to the urban centers of the north. For years she worked as a housecleaner until Willie Dixon discovered her in 1963 sitting in with a band at a South Side nightclub. She had an R&B hit with Dixon's Wang Dang Doodle in 1966 and was one of the first Chicago blues artists to work the white clubs on the city's North Side.

She signed with Alligator in 1975 and received Grammy nominations for eight of her nine Alligator albums (she won a Grammy in 1984 for the live multi-artist album Blues Explosion on Atlantic Records). She won a record 29 Blues Music Awards (the Grammy of the blues world) and in 1999 was inducted into the Blues Foundation's Hall Of Fame. "There are many kings of the blues," said The Boston Globe, "but only one queen."