Biopolymers have become very popular; because they are biodegradable, biocompatible, non-toxic, and renewable. As a result of its intrinsic reactive amino groups, chitosan stands out among other biopolymers. Chemical reactions have been used to modify chitosan using these amino groups to accomplish a variety of structural modifications. The imine functionalization of chitosan, CSBs (chitosanbased Schiff bases) are recommended for essential practice in water treatment, catalysis, bioscience, sensors, etc. CSBs are prepared by condensation reaction between carbonyl compounds and chitosans amino groups. This review first introduces the synthesis of different types of Schiff base ligands and then CSBs. Then the biological utilization of CSBs, including their tissue engineering capabilities, antimicrobial, antibacterial, anticancer, drug-carrying, and antioxidant are discussed. Later, CSBs are shown to be applied to catalysis, adsorption, and sensors.