The scarcity of water has motivated diverse research efforts toward developing efficient techniques for the treatment of wastewater for its reuse. The applications of conventional wastewater treatment technologies, such as chemical precipitation, ion exchange, flotation, flocculation and coagulation, membrane filtration, etc., have been identified with diverse limitations. The commonest of them include high investment and operational costs, the formation of toxic by-products and sludge generation. Ionic liquids (ILs) have been used in numerous analytical and industrial extraction processes; however, their potential in the treatment of wastewater is yet to be fully exploited. This chapter, therefore, explores the applications of various ILs in wastewater treatment and proposes their versatility in the deployment of effective, selective, and rapid extraction processes for the removal of diverse water pollutants. However, the application of technologies based on the use of ILs possesses various challenges, which include a choice of an appropriate ionic liquid, high testing requirement for private applications, disposal, the regeneration process of ILs, scalingup of the whole removal of pollutants, and technological applications.