Human fetal γ-globin gene is developmentally silenced around the birth, and reactivation of γ-globin gene in adulthood sheds new light on ameliorating symptoms of hemoglobin disorders, such as sickle cell disease (SCD) and β-thalassemias. However, the precise regulation process of γ-globin remains incompletely understood. Here, we found that a new protein directly interacted with SOX6 and exerted a significant repression effect on the expression of γ-globin gene in erythroid cells. Further studies have demonstrated that it bound directly to γ-globin gene promoter via octamer binding motif, which in turn suppressed the transcriptional activity of γ-globin gene promoter. Thus, these data indicate that this new protein acts as a novel transcriptional repressor in the regulation of γ-globin gene expression through direct promoter binding, implying a potential alternative therapeutic target for the treatment of SCD and β-thalassemias.