Notch signaling has been reported to be involved in several types of malignant tumors. However, the role and activation mechanisms of Notch signaling in oral squamous cell carcinoma (OSCC) remain poorly characterized. The present review focuses on the dual role of Notch signaling in OSCC. A number of expression and functional analyses demonstrated that Notch1 plays a crucial role in development and progression of OSCC. On the other hand, a tumor suppressive role of Notch1 was also suggested from studies, based on deep sequencing of cancer genomes. Interestingly, although some Notch1 mutations overlap in tumors from Caucasian and Asian patients, the overall spectrum of such mutations is vastly different between these cohorts. Accumulating evidence suggests that variation of Notch1 mutation signature may determine the role of Notch signaling in OSCC. As Notch is thought to act as an oncogene in a subset of OSCC, but also has a tumor suppression role, the role of Notch in OSCC seems to be highly context dependent.