With the advancement of medical research, the source and preparation of biological materials have gradually attracted attention. Hydrogels prepared from natural polysaccharides have been extensively applied in the medical field. The biocompatibility, excellent degradability and low toxicity of chitosan have favored the use of chitosan hydrogels as prospective carriers for drug delivery. Special chitosan hydrogels that effectively release target drugs based on different environmental stimuli have also been developed. This article reviews recent research progress in the development of chemical and physical chitosan hydrogels for drug delivery. In particular, preparation methods together with the chemical and physical properties of chitosan hydrogels are summarized. We also discuss multiple mechanisms of drug release from chitosan hydrogels. Finally, we highlight the future prospects of chitosan hydrogels in medical research.