Robert Brown was reputedly the illegitimate son of Frank Broonzy, who also fathered Big Bill Broonzy. Broonzy often joked that Sam was his half brother when they performed together.
Sam was raised in Arkansas, working on a farm. He moved to Memphis in the early '20s to play the blues. While in Memphis, he met Sleepy John Estes and Hammie Nixon and the trio played street corners, collecting tips from passer-bys. In 1932, Washboard Sam moved to Chicago. Initially he played for tips, but soon he began performing regularly with half brother Big Bill Broonzy. Within a few years, Sam was supporting Broonzy on the guitarist's Bluebird recordings. Soon, he was supporting a number of different musicians on their recording sessions, including pianist Memphis Slim and bassist Ransom Knowlin, and a handful of saxophone players, who all recorded for Bluebird.
He was a mainstay of a shifting group of musicians centred on A & R man Lester Melrose, Slim, Broonzy, Sam, Tampa Red and Jazz Gi llum, often played on each other's sessions and in ad-hoc groups like the Hokum Boys and the State St Swingers, this was later called the Bluebird Beat. In 1935, Washboard Sam began recording for both Bluebird and Vocalion Records, often supported by Broonzy.
Throughout the rest of the '30s and the '40s, Sam was one of the most popular Chicago bluesmen, selling numerous records and playing to packed audiences. As a testament to his popularity RCA/Bluebird issued nearly everything he recorded for them. His deep strong voice overcame the stylistic limitation of his chosen instrument.