Boron (B) separation from photovoltaic silicon (Si) remains a research challenge in the recycling field. In this study, a novel B-removal process was developed using thermal plasma treatment coupled with steam and hydrogen gases. Experiments were performed on artificially B-doped Si using various plasma conditions of mixed argon (Ar)/steam/hydrogen gases and varied refining time. The B concentration in all of the samples decreased with increasing refining time. The use of the plasma mixed with Ar/steam/hydrogen gases resulted in a significant improvement of the efficiency of B removal compared with the Ar/steam plasma refining. In addition, with increasing steam content in the plasma with mixed Ar/steam/hydrogen gases, the B-removal rates increased.