In this period of water scarcity, wastewater originating due to urbanization and industrialization is the principal cause of water contamination. Pollutants in wastewater present an imminent risk to the health of the environment, accelerating the need for efficient wastewater treatment in developing economies. It is imperative to develop and implement improved wastewater treatment techniques that are both efficient and cost-effective. Among various treatment technologies, nanotechnology has been attracting the attention of researchers because of its potential to improve waste water treatment efficiency. Only a small number of studies emphasized metal oxide NPs and their potential in wastewater decontamination. Nanoparticles (NPs) possess the ability to eliminate heavy metals, organic compounds, and inorganic contaminants from polluted water. Metal oxides are highly distinct category of materials characterized by their exceptional features like improved surface area, relatively low concentration, readily separable after the treatment process, etc. In this chapter, we emphasized iron oxide, copper oxide, titanium oxide, zinc oxide, and silver oxide NPs for waste water treatment processes. This article certainly provides a comprehensive overview of the removal of the contaminants by using above-mentioned metal oxide NPs.