This study explores the expression of Yes-associated protein (YAP), a key effector of the Hippo pathway, across the spectrum of oral carcinogenesis. Using immunohistochemistry on ethically sourced samples of normal oral mucosa, leukoplakia, and oral squamous cell carcinoma (OSCC), we observed a clear, progressive rise in YAP staining from healthy tissue to dysplasia and finally to OSCC. Dysplastic lesions showed stepwise increases in YAP intensity correlating with severity, while OSCC displayed the highest expression. Both nuclear and cytoplasmic staining were evident, with nuclear positivity (>10%) highlighting YAP's active transcriptional role in promoting cell growth and malignant transformation. These findings suggest that YAP is a significant biomarker and potential driver of oral cancer progression.