<p>Polysaccharide-derived carbon quantum dots (CQDs) have garnered significant attention as innovative nanomaterials, owing to their exceptional biocompatibility, minimal toxicity, and remarkable fluorescent properties. These attributes render them highly suitable for a range of biomedical applications, particularly in the realm of theranostics, where diagnostic and therapeutic functionalities converge. Utilizing renewable and abundant polysaccharides—such as chitosan, cellulose, starch, pectin, alginate, dextran, and heparin—as carbon sources, these CQDs benefit from inherent functional groups like hydroxyl and carboxyl. These groups enhance the stability, solubility, and functional versatility of the CQDs, expanding their applicability in bioimaging, targeted drug delivery, and cancer therapy. Moreover, these nanomaterials have demonstrated potential in controlled drug release systems and tissue engineering, reinforcing their dual role in diagnostics and therapeutics. This review delves into the latest advancements in the synthesis of polysaccharide-based CQDs, highlighting preclinical studies that underscore their efficacy in imaging, drug delivery. With sustained research and technological innovation, polysaccharide-derived CQDs are poised to make significant contributions to personalized medicine, offering more effective and tailored treatment strategies across a spectrum of diseases.</p> Graphical Abstract <p>Theranostic applications of carbon quantum dots</p> <p></p>