Marine-derived chitosan has been widely examined for its use in developing biomedical materials. Not only is it non-toxic, biocompatible, and degradable, it has also shown unique antimicrobial properties. The antimicrobial properties of chitosan are restricted by neutral and physiological conditions because it is insoluble in water and its pKa values is 6.5. One solution to this problem is to graft chemically modified groups onto the backbone of chitosan. The aim of this paper is to review the mode of antimicrobial action of chitosan and chitosan derivatives. Using chitosan alone may not meet the demands of various applications. However, the introduction of additional polymers and antimicrobial agents is commonly used to enhance the antimicrobial potential of chitosan-based biomaterials. Chitosan-based composite biomaterials have been developed that allow diversified formulations to broaden applications, including nanoparticles, hydrogels, films, sponges, fibers, or even microspheres. These along with recent advances on chitosan-based composite biomaterials used for wound healing, food packaging, textile sector, 3D printing and dental materials, were reviewed in detail.