Nanocomposites have emerged to be very effective materials for the removal of pollutants because of their remarkable physicochemical characteristics. These materials integrate the enhanced properties of nanomaterials, such as the high surface area, variable pore size, and higher reactivity with the mechanical stiffness of the conventional composites. This chapter provides a comprehensive overview of different types of nanocomposites, including polymer-based, ceramic-based, and metal-based variants, each contributing uniquely to pollutant removal processes. The core mechanisms by which nanocomposites remove pollutants, such as adsorption, photocatalysis, chemical reduction, and membrane filtration, are discussed in detail, highlighting their specific role in treating wastewater. Case studies will showcase the real-world scenario and efficacy of different nanocomposites in removing heavy metals and organic contaminants. In addition to this, the chapter critically addresses the practical challenges associated with stability, durability, economic viability, potential toxicity, and environmental impact of nanocomposites. Overall, this chapter emphasizes the critical role of nanocomposites in advancing eco-friendly and effective wastewater treatment technologies for sustainable environmental applications.