Abstract <p>The presence of pollutants in water bodies compromises the aquatic ecosystem and public health. Crayfish waste is being discarded from the seafood market in large quantities annually. Crayfish shells can be valorized as biochar to remove water pollutants due to their availability and low cost. This paper review aims to highlight its preparation as an environmental-friendly adsorbent. Adsorption is a preferred process to remove various pollutants from water. The treatment methods and physicochemical properties of the derived biochar were highlighted, and the adsorption capacities of some model pollutants were compared and discussed. The calcium moieties and chitin in biochar aid in the adsorptive removal of target pollutants. Besides, the present challenges and future directions of crayfish shell biochar were presented to shed insight into practical applications in wastewater treatment.</p>