In this study, the potential effects of juglone, also known as PIN1 inhibitor, on oral cancer and carcinogenesis were investigated at the molecular level. 4-Nitroquinoline N-oxide (4-NQO) was used to create an oral cancer model on animals. Wistar rats were divided into five groups; Control, NQO, Juglone, NQO+J, and NQO+J*. The tongue tissues of the rats were isolated after the experiment, morphological changes were investigated by histological examinations, and the molecular apoptotic process was investigated by rt-qPCR and Western blot. Histological results indicate that tumors are formed in the tongue tissue with 4-NQO, and juglone treatment largely corrects the epithelial changes that developed with 4-NQO. It has been determined that apoptotic factors p53, Bax, and caspases are induced by the effect of juglone, while antiapoptotic factors such as Bcl-2 are suppressed. However, it was observed that the positive effects were more pronounced in rats given juglone together with 4-NQO. The use of PIN1 inhibitors such as juglone in place of existing therapeutic approaches might be a promising and novel approach to the preservation and treatment of oral cancer and carcinogenesis. However, further research is required to investigate the practical application of such inhibitors.