Increase in population and climate change are predicted to cause a significant increase in problems regarding water. In the near future, maintaining water quality will be the primary focus. Rather, regulations governing wastewater remediation and reuse will become more stringent due to scarcity or contamination of water. Furthermore, in order to take into consideration the new contaminants that have been found in groundwater, the quality of drinking water requirements need to be raised. Only with the development of new, more advanced, and environmentally sustainable water remediation technologies will these goals be achieved. Conventional wastewater remediation involves either physical, chemical, biological, or, in certain situations, a combination of these techniques. The contaminants, especially organic materials, cannot be completely removed by the wastewater remediation processes currently in use. Further treatment is required because these chemical compounds frequently exhibit resistance to conventional treatment techniques. In recent decades, advanced oxidation processes (AOPs) have drawn a lot of attention from researchers because of the increasing amount of more harmful pollutants in water sources. Advanced oxidation processes (AOPs), which are chemical oxidation techniques, employ strong transient species such as hydroxyl and sulfate radicals. Energy sources like solar, electrical, or acoustic energy, as well as basic chemicals like ozone, H2O2, etc., can create these species from water with or without the aid of a suitable catalyst. The current state of research on advanced oxidation processes (AOPs) is being enhanced by nanomaterials. An overview of nanoparticles and nanocatalysts for the treatment of wastewater is given at the beginning of this chapter. The most significant AOPs are then discussed, including the removal of water contaminants via ozone, UV/H2O2, Fenton processes, persulfate, chlorine and NH2Cl-based processes and heterogeneous photocatalytic processes. These processes underpin the benefits of AOPs over more conventional methods for treating contaminated water. A detailed discussion of how nanomaterials are now coupled to some of these AOPs are presented. The significance of the nanomaterials’ adsorbent/absorbent function in these processes is also explored, in addition to their active participation in the decomposition of water contaminants/pollutants through AOPs. The comprehensive advantages and disadvantages of each generating approach are also discussed with emphasis toward industrial applications. To summarize, this chapter provides an extensive overview of how various approaches give rise to varied types of radicals; in addition to the principles and mechanisms of production, the economic and environmental consequences of the various strategies are also explored. The key objective of this chapter is to provide easy access for academicians and researchers associated with the field of wastewater treatment using nanomaterials in combination with different AOPs and/or hybrid AOPs.