Urbanization and technical advancements have given rise to large wastewater-generating industries like biotechnology, petrochemical, agriculture, and pharmaceuticals. This effluent is difficult to treat because of its diverse composition, which includes organic compounds, colors, pharmaceutical waste, residual contaminants, and hazardous substances. Conventional wastewater treatment methods, including ion exchange, adsorbents, reverse osmosis, and electrostatic precipitation, have the disadvantages of being expensive, having a small recycling capacity, and being inefficient. Photocatalytic techniques have shown promising effect in treating wastewater, especially when contaminated with hazardous dyes. These dyes are highly dangerous to the environment and public health. Researchers have created environmental friendly techniques, like photocatalytic degradation of metal-based nanomaterials (NMs), to effectively and efficiently break down these harmful pollutants. With their strong reactivity, functionalization, and size-dependent qualities, straight band gap, high optical absorption coefficient, low cost, and low toxicity, NMs such as metal nanoparticles (NPs), oxides, carbon compounds, zeolite, and filtration membranes are perfect for treating wastewater. The efficacy of photocatalytic NPs can be increased by coupling these NPs with appropriate species, which may help to avert further water shortages. Research in this area can help address the limitations of photocatalytic NPs in wastewater treatment. The several photocatalytic NM metal-based and metal-free that have been investigated for the treatment and purification of water and wastewater are discussed in this review. This review opens up new directions for the study of water treatment by offering insightful information on how solar energy is transformed for photocatalytic reduction of hazardous metal ions and degradation of dye-contaminated wastewater.