Transitional metal dichalcogenides (TMDCs) have lately attracted attention as viable two-dimensional (2D) materials capable of enhancing the performance of membrane-based technologies for wastewater treatment. The dispersion of TMDCs in nanocomposite membranes seems to have established diverse alternatives to control membrane surface properties as well as the antifouling behaviour. This is possible due to the ability to manipulate the 2D structure of TMDCs along the processing stage, which creates the necessary building block to design and fabricate membranes with improved separation performance. Recent research has revealed that 2D TMDCs possess better performance indicators than graphene and its functional derivatives due to their outstanding mechanical, biological, and physicochemical properties which could be inherent when blended with polymeric materials to formulate membrane composites. Very few reviews have tackled a detailed discussion about the separation performance of TMDCs based membranes for wastewater treatment and in here, a detailed discussion is made. In this review, TMDC nanomaterials and their polymeric membrane nanocomposites are discussed in detail for water remediation and wastewater treatment. Several TMDCs are described with regard to their low-cost synthesis procedures in addition to vital characterization techniques utilized to analyse these materials. This is followed by a thorough discussion about synthesis and characterization employed to analyse the effect and dispersion of TMDCs in polymeric membranes to form nanocomposite membranes. Finally, an analysis for the role of using TMDC-based nanocomposite membranes for wastewater treatment is made and the rejection mechanisms that have been concluded from recent studies are also discussed. This review has focused on novel areas that are overlooked by a few reviews published in this area, with regard to using TMDCs in modifying polymeric membranes for water remediation and wastewater treatment.