Sintilimab, a fully human immunoglobulin G4 monoclonal antibody targeting the programmed cell death receptor 1 (PD-1) pathway, has emerged as significant in cancer immunotherapy, demonstrating promising antitumor effects in various malignancies. The present review summarizes the current clinical data, highlighting the role of sintilimab in treating various types of cancer, including non-small cell lung cancer, liver cancer, gastric cancer and neuroendocrine tumors. The review also explores the mechanism of action of sintilimab, its structural and pharmacokinetic properties and its safety profile, which includes a comprehensive analysis of immune-related adverse events. Notably, the high binding affinity of sintilimab to PD-1 and its fully humanized nature contribute to its potent immunotherapeutic effects and favorable safety profile. Clinical trials have shown that sintilimab, either used as a monotherapy or in combination with chemotherapeutic agents, can significantly extend progression-free and overall survival in patients with advanced cancers. Furthermore, the economic implications and accessibility of sintilimab, particularly in resource-limited settings, are discussed. The current review reports on the innovative potential of sintilimab in shaping future cancer treatment strategies and emphasizes the need for personalized therapy based on individual patient biomarkers. The study reveals that sintilimab is not only a viable alternative to existing PD-1 inhibitors, but also a promising candidate for further research and development in immuno-oncology.