<p>This Reprint guest-edited by Dr. Dawei Zhang and Xianzhi Kong collates a collection of research works dedicated to the advancement of chitosan and chitin with particular emphasis on hydrogels nanofibers smart materials nanocomposites foams and dressing materials. This Special Issue focuses on the preparation and application of materials based on chitosan and chitosan with the aim of presenting the latest research advances in the biomedical applications of chitosan and chitin and highlighting the potential for further innovative research in this area.</p>