Nanocomposites have garnered significant attention in wastewater treatment due to their unique physicochemical properties, such as high surface area and enhanced reactivity. This review outlines recent advances in the development of nanocomposites for environmental remediation, covering synthesis techniques, structural diversity, and practical applications. Commonly employed materials include layered double hydroxides (LDHs), carbon-based nanomaterials like graphene and carbon nanotubes, metal oxide hybrids (e.g., ZnO, Fe₃O₄, and TiO₂), polymer-functionalized frameworks, and emerging platforms such as metal–organic frameworks (MOFs) and MXenes. Synthesis methods such as co-precipitation and hydrothermal processing play a critical role in determining particle dispersion and morphology. In particular, LDH-based nanocomposites exhibit strong redox ability and ion-exchange characteristics, making them effective for heavy metal detection and the degradation of organic pollutants through adsorption, photocatalytic, and electrochemical pathways. Despite these advantages, challenges including material leaching, regeneration efficiency, scalability, and long-term environmental safety persist. Nanocomposites present a versatile platform with considerable potential for efficient, scalable, and sustainable wastewater treatment. By addressing current limitations such as emerging contaminants like pharmaceutical residues, per- and polyfluoroalkyl substances (PFAS), and microplastics, nanocomposites can further enhance water purification and environmental cleanup, increasing their practical applicability. Future research should prioritize green synthesis methods, pilot-scale validation, and regulatory assessments to bridge the gap between laboratory studies and real-world wastewater treatment applications.