Osteoarthritis (OA) is a common joint disease, which is mainly characterized by the degeneration of articular cartilage, inflammation of the synovial membrane of the joint, and changes in the surrounding bone tissue. With the increase of age and weight, the incidence of OA gradually increases, which seriously affects the quality of life of patients. The primary pharmacological treatments for OA include analgesics and non-steroidal anti-inflammatory drugs. However, these medications primarily provide symptomatic relief and are associated with significant side effects. Chitosan, derived from the deacetylation of chitin, has excellent biocompatibility, biodegradability, anti-inflammatory and antioxidant properties, and can promote the repair of articular cartilage. Chitosan can be used as a viscosupplement, drug carrier, cartilage tissue engineering scaffold or other forms. In this review, we systematically summarize the applications of chitosan and its derivatives in the treatment of OA.