Purpose <p>This review aims to provide a comprehensive analysis of the role of functional peptides in targeted cancer therapy, with a focus on their molecular mechanisms, delivery strategies, and clinical development. The key research question addressed is how functional peptides can overcome current limitations in cancer treatment, including poor specificity, drug resistance, and systemic toxicity.</p> Methods <p>A thorough literature review was conducted using recent peer-reviewed publications, clinical trial data, and preclinical studies related to peptide-based cancer therapeutics. The review critically examines different classes of functional peptides, including tumor-homing, pro-apoptotic, immune-modulating, and cell-penetrating peptides, and discusses their integration into various delivery platforms.</p> Results <p>Functional peptides demonstrate significant potential in improving tumor selectivity, intracellular drug delivery, and immune modulation. Delivery strategies such as peptide-drug conjugates, nanoparticle-loaded peptides, lipidation for serum stability, and tumor-penetrating peptides like iRGD enhance pharmacokinetics and therapeutic efficacy. Advances in peptide-based cancer vaccines, immunotherapies, and stealth nanoparticle encapsulation further reduce off-target effects and immunogenicity. Several of these approaches have progressed into clinical trials, reflecting their translational relevance.</p> Conclusion <p>Functional peptides represent promising agents for next-generation cancer therapy due to their specificity, safety, and adaptability. Continued research into optimizing peptide design, delivery systems, and manufacturing scalability is essential to fully harness their potential in precision oncology and personalized medicine.</p>