The worldwide growth of the global technology industry has significantly contributed to the accumulation of harmful pollutants in the environment. Zinc oxide (ZnO), a semiconductor material, has attracted considerable attention as a photocatalyst due to its eco-friendly nature, biocompatibility, wide availability, and durability in removing hazardous contaminants. This chapter provides a thorough analysis of the results of recent advancements in ZnO-based heterostructures as photocatalysts for treating organically polluted wastewater. Moreover, it analyzes substantial progress made in addressing the problems related to pure ZnO. Considerable work has been done to accomplish metal/non-metal doping, create a heterojunction, and integrate ZnO with a small band gap material. These efforts aim to increase photocatalytic performance and extend ZnO’s absorption spectrum from the ultraviolet to the visible range. The mechanisms of charge separation and transfer, strategies for improving photocatalytic activity, and the enhanced light-harvesting capabilities of ZnO are thoroughly discussed. Futhermore, this chapter emphasises the role of ZnO-based photocatalysts in wastewater treatment and identifies promising directions for future research. It is crucial to choose plentiful and non-toxic materials to ensure both economic effectiveness and environmental safety. Moreover, given the abundant availability of solar energy, future studies should prioritize the use of natural sunlight for illumination instead of artificially generated solar light. This chapter of the book explores prospective improvements and compelling future strategies for utilizing modified ZnO to serve as photocatalyst.