The production of biochar from biogas digestate is one of the effective ways to achieve its safe disposal and resource utilization. The component structure and physicochemical properties of digestate-derived biochar are optimized to some extent with anaerobic digestion of digestate. Therefore, the digestate-derived biochar with low cost, wide source, good adsorption and catalytic properties is applied to remove pollutants from water. In this paper, the feedstock sources, preparation and modification methods of digestate-derived biochar are summarized. Besides, the current status of digestate-derived biochar as adsorbent or carbon-based catalyst in water treatment is discussed. In addition, the mechanism of pollutant removal by digestate-derived biochar is described. Finally, some problems and challenges of the application of digestate-derived biochar in water treatment is proposed, and the development direction of its application in aquatic environment is pointed out.