Osteosarcoma, a malignant bone tumor, faces significant treatment challenges. Enhancer of zeste homolog 2 (EZH2) shows aberrant expression in various tumors including osteosarcoma, which is identified as a potential therapeutic target. The anti-cancer efficacy of EZH2 inhibitor GSK126 has attracted attention, yet its impact on osteosarcoma cells was not fully understood. The study investigated the effects of GSK126 on osteosarcoma cells, particularly in apoptosis, autophagy, and cell motility. Our findings revealed that GSK126 induced apoptosis and autophagy, evidenced by increased markers like cleaved caspase-3 and LC3-II, and decreased cellular migration, through downregulation of the Fuse Binding Protein 1 (FBP1)/C-Myc axis. These findings suggest GSK126 as a promising therapeutic against osteosarcoma, offering a dual action of promoting cell death and hindering migration.