This review explores the advancements in nanoparticle-based technologies for water and wastewater treatment, focusing on their synthesis methodologies, intrinsic properties, and versatile applications. It highlights the use of various nanoparticles, including metal nanoparticles and carbon-based nanomaterials, as well as hybrid nanocomposites, in eliminating contaminants from water and wastewater matrices. The review also discusses the underlying mechanisms governing pollutant removal processes, such as adsorption, catalysis, and membrane filtration, and addresses the environmental implications and challenges associated with the widespread deployment of nanoparticle-based water-treatment technologies. Additionally, it provides insights into the potential of nanoparticles and nanocomposites in mitigating water-related challenges and presents recommendations for future research and technological advancements in this domain.This review explores the advancements in nanoparticle-based technologies for water and wastewater treatment, focusing on their synthesis methodologies, intrinsic properties, and versatile applications. It highlights the use of various nanoparticles, including metal nanoparticles and carbon-based nanomaterials, as well as hybrid nanocomposites, in eliminating contaminants from water and wastewater matrices. The review also discusses the underlying mechanisms governing pollutant removal processes, such as adsorption, catalysis, and membrane filtration, and addresses the environmental implications and challenges associated with the widespread deployment of nanoparticle-based water-treatment technologies. Additionally, it provides insights into the potential of nanoparticles and nanocomposites in mitigating water-related challenges and presents recommendations for future research and technological advancements in this domain.