Nano-materials are defined as structured components with dimensions ranging from approximately 1-100 nm. Because a smaller mass of material has increased specific surface area compared with conventional macroscale materials that can achieve the same objective, the consumption of raw materials is minimized significantly, with cost savings. Nano-sized iron in particular has many applications in the medical, biosensing, food, energy, and environmental fields because of its versatile properties and high level of catalytic activity. The green synthesis of nano-scale iron materials, especially from plants, has garnered substantial attention due to its ease of application, eco-friendly nature, and economy. Researchers and scientists worldwide have sought to assess the synthesis of iron nano-materials and the effectiveness of iron synthesized as such for the removal of environmental pollutants. These research efforts have involved numerous laboratory and field techniques. Green synthesis involves mostly the use of plants and the application of nano-sized iron materials for the removal of heavy metals, metal ions, dyes, chlorinated organic compounds, bacteria, and other pollutants such as nitrate, phosphate, chemical oxygen demand, and total organic carbon present in industrial wastewater, surface water, and groundwater. These themes will be explored in this paper.