<p>Aqueous zinc-ion batteries (AZIBs) have emerged as a core candidate system for next-generation electrochemical energy storage technologies, owing to their inherent advantages such as high safety, low cost, and environmental compatibility. However, their industrialization is still constrained by dual technical bottlenecks in both the positive and negative electrodes: zinc anodes are prone to dendrite growth, hydrogen evolution, and corrosion during charge-discharge cycles, while cathode materials suffer from active component dissolution and electrode structural instability over prolonged cycling. These issues collectively degrade device performance and severely hinder the practical application of AZIBs. Chitosan, a renewable and biodegradable natural polysaccharide, possesses key electrochemical functional properties including ion transport regulation, zinc dendrite inhibition, and electrode/electrolyte interface stabilization, offering a green and efficient material strategy to address these critical bottlenecks. It demonstrates significant application potential in the field of AZIBs. Based on this, this paper systematically reviews the latest research progress on chitosan and its modified composite materials in the functional modification of AZIBs separators, interface modification of positive/negative electrodes, and electrolyte performance optimization. Additionally, it addresses current challenges and provides insights into future development directions, aiming to offer theoretical references and technical insights for the high-performance, long-cycle stability, and green development of AZIBs.</p>