Ionic liquids (ILs) as well as closely related deep eutectic solvents (DESs) have been the most promising discoveries in the ?Green Chemistry? world in recent years as types of solvents. Deep eutectic solvents are received as potential alternatives to the conventional organic solvents with other advantages such as renewability, reusability, biodegradability, nontoxicity, large-scale availability, having very low vapour pressure, low flammability and easy in preparation. Chitin is the second most abundant biopolymers in the nature that can be extracted from many aquatic and terrestrial organisms also some of the microorganisms. Chitin and its derivatives have applications in many fields such as medical, food-beverages, agriculture and cosmetics. This review reports the major contributions of DESs in chitin and chitosan related studies and summarizes recent advances in some applications such as extraction media, bio-film fabrication, nanomaterial preparation, chitosan methylation, chitin dissolution, composite material preparation.