Organic and toxic pollutants released by industries into water bodies are a major cause of water pollution. Organic pollutants contaminate water resources and affect aquatic lives, including phytoplanktons and zooplanktons. Conventional wastewater treatment methods such as disinfection via chemicals, UV treatments and filters may be costly, toxic to aquatic lives, and/or unable to routinely deliver the acceptable wastewater regulatory standards for discharge. Advancements in the field of nanotechnology provides opportunity to utilize semiconductor nanomaterials as photocatalysts capable of converting organic pollutants into carbon dioxide and water. However, the potential toxicity of these nanomaterials to water bodies becomes a major concern, especially for large-scale applications. Biosynthesized nanoparticles are seen as a more environmentally benign alternative to conventional chemically synthesized semiconductor nanoparticles. This chapter provides an overview of biosynthetic approaches to nanoparticle generation and their photocatalytic properties. Also, the performance and the mechanism of photocatalytic nanoparticles for organic pollutant removal in wastewater treatment are discussed.