Membrane separation is a promising method for efficient water treatment due to its ease of operation, minimal environmental impact, and cost-effectiveness. However, it has limitations in terms of permeability and solute rejection, influenced by membrane material and operating conditions. Mixed-matrix (ceramic plus polymer) membranes with uniformly dispersed nanomaterials and thin-film composite membranes with nanomaterials in the top layer or substrate improve hydrophilicity and microstructure. This chapter focuses on developing and characterizing nanofiltration membranes using metal oxide nanomaterials and polymer–graphene nanocomposites on ceramic support for heavy metal removal from polluted water. It covers membrane types, fabrication methods, properties of graphene oxide (GO), and characterization techniques. Various nanomaterial additives such as TiO2, ZrO2, zeolites, and metal–organic frameworks are mentioned. Challenges include cost, nanoparticle aggregation, defect control, and gaining insights into the interactions between nanoparticles and polymers, hindering low-cost nanocomposite membrane development. This chapter also covers the primary techniques for synthesizing and preparing materials, such as phase inversion, dip coating, spin coating, and interfacial polymerization. Recent advances and applications of these techniques are detailed. Parameters for optimal polymer–graphene nanocomposite membranes and factors affecting their performance in dye and heavy metal ion removal from wastewater are also discussed. Furthermore, the future pathway toward the development of polymer–graphene nanocomposite-based nanofiltration membranes for water treatment and decontamination of wastewater in large scale is suggested.