The majority of anticancer drugs are of natural origin. However, it is unknown whether licochalcone A is cytotoxic towards oral squamous cell carcinoma (OSCC) cells. The goal of this study was to investigate the cytotoxic effects of licochalcone A on the human OSCC SCC-25 cells and to identify the underlying molecular mechanism. Exposure of SCC-25 cells to licochalcone A dose- and time-dependently decreased cell viability by arresting cell cycle at the S and G2/M phase as well as inducing apoptosis. Furthermore, the proapoptotic activity of licochalcone A was revealed by DNA fragmentation. Concomitantly, we observed activation of the effector caspases-3, induced by activation of the initiator caspases -8 and -9, which subsequent trigger both death receptor pathway and the mitochondrial apoptotic pathway in licochalcone A-mediated SCC-25 cell apoptosis. Besides, treatment with 50 μg/mL of licochalcone A for 36 h led to the cleavage of PARP, an indicator of apoptosis induction. Therefore licochalcone A may be a good candidate for development as a possible chemopreventive agent against OSCC.