Thomas was born in Houston, Texas, and displayed an early talent for blues playing and composition. He was one of several musicians in his family. His brother George W. Thomas was also a skilled piano player, while his sister Sippie Wallace and niece Hociel Thomas were singers of note.
Though he died at a young age, Thomas was nonetheless a strong influence on the Chicago boogie-woogie school of pianists. Albert Ammons and Meade Lux Lewis both cited him as an influence. His most famous track is likely "Suitcase Blues" (8958-A Okeh 8227), which was issued on CD in 1992 as part of the box set, Roots 'N Blues: The Retrospective. The Thomas brothers also co-wrote "The Fives", which Ammons and Lewis cited as an essential boogie-woogie number.
Thomas recorded under his own name, and as an accompanist to Hociel Thomas, Sippie Wallace, Lilian Miller and Sodarisa Miller. In 1926, he recorded a session with Hociel Thomas and Louis Armstrong. The songs recorded on that occasion were "Deep Water Blues" (9519-A Okeh 8297), "Lonesome Hours" (9522-A Okeh 8297), "Listen To Ma (9521-A Okeh 8346), and "G'wan, I Told You" (9520-A Okeh 8346). The first three are listed as having been composed by "Thomas", though it is not clear if this refers to Hersal or his brother. He also worked in session with King Oliver.
Sippie Wallace recorded seven of his compositions: "A Jealous Woman Like Me", "A Man For Every Day Of The Week", "Dead Drunk Blues", "Have You Ever Been Down?", "I Feel Good", "Shorty George Blues" and "Trouble Everywhere I Roam".