Following the closedown of the Storyville area of New Orleans, he moved to Chicago in about 1921, and was joined there by his sister Beulah "Sippie" Wallace, who also became a performer, and by his brother Hersal, though his mother remained in Houston until her death. By now the sole proprietor of his publishing company, Thomas reissued some of his earlier compositions and also played with local groups and accompanied singers, including Sippie. In all he was credited with over 100 compositions. In 1922, he published "The Fives", co-written with brother Hersal, and inspired by a train traveling between Chicago and San Francisco. This was "the first published boogie-woogie with a boogie bass line throughout," and "helped to inspire a generation of boogie-woogie pianists" such as Meade Lux Lewis and Albert Ammons. The following year, he is widely credited with recording another of his compositions, "The Rocks", for Okeh Records, which contains the earliest recording of a walking bass. The recording was credited to Clay Custer, generally regarded as a pseudonym, but there is some disagreement over whether the performer was Thomas himself, or another pianist, possibly Hersal Thomas or Harry Jentes. In Chicago, George Thomas also recorded as an accompanist for Tiny Franklin on Gennett Records, and had his own jazz group, the Muscle Shoals Devils, who made recordings that were not released. Thomas was respected as a composer, and was quoted in the "Music Trade Review" in 1924:The world wants dancing music, and, tunefulness apart, wants something not reminiscent of hundreds of dances that have gone before... It is a waste of energy for the composer or publisher to plagiarize a winner. The music buying public is too wise today. And people who love to dance, even if they do not play music, are quick to appreciate novelty in melody and theme in a new song. George Thomas continued to publish compositions after his brother Hersal's sudden death, aged 20 in 1926, but his output diminished in the late 1920s. His last recordings were with singer Lillian Miller for Gennett in 1928. Although in her later years Sippie Wallace claimed that George Thomas had died in about 1930 as a result of an accident involving a streetcar, official records including his death certificate state that he died in Chicago in 1937, from breaking his back falling down stairs, possibly after a fire had broken out. He was buried at Restvale Cemetery in Alsip, Illinois.