Cutaneous squamous cell carcinoma (cSCC) is the second most common non-melanoma skin cancer that has been on the rise in recent times, particularly among older individuals. Cornulin (CRNN) is increasingly recognized as an oncogene involved in developing various types of tumors. However, the precise contribution to cSCC remains unclear. Our study observed a significant increase in CRNN expression in cSCC samples compared to healthy skin. CRNN expression in the SCL-1 cell line derived from cSCC was reduced, leading to a halt in cell growth during the transition from the G1 phase to the S phase. This reduction inhibits cell division, promotes cell death, and decreases cell invasion and migration. CRNN overexpression has been found to enhance cell growth and prevent cells from undergoing natural cell death, and the cancer-promoting effects of CRNN are linked to AKT activation. Using a mouse xenograft model, we demonstrated that the inhibition of CRNN led to a decline in cSCC tumor growth in a living organism, providing evidence of CRNN's involvement in cSCC occurrence and development. This study establishes a foundation for evaluating the effectiveness of CRNN in treating cSCC, enabling further investigation in this area.