Wastewater management is crucial for protecting the environment, especially with the rise of industrialization and urbanization, which contribute to the release of pollutants into water systems. One innovative method of addressing this issue is through bioremediation, where fungi play a key role. Although bacteria are more commonly used in biological wastewater treatment, fungi offer a sustainable and cost-efficient alternative. Fungi release various extracellular enzymes, such as laccase, catalase, and peroxidase, making them highly effective at breaking down waste in nature. These enzymes enable fungi to treat wastewater from industries like textiles, breweries, food processing, and hospitals, as well as pollutants like polycyclic aromatic hydrocarbons and pesticides. Fungi are particularly effective at removing heavy metals due to their cell walls containing metal-binding functional groups like hydroxyl, amine, and carboxyl. Their filamentous structure, which forms pellet-like masses, enhances the treatment process by improving oxygen and nutrient transfer. Fungi also assist in algae removal during water treatment through co-palletization. This chapter explores the various fungal mechanisms for wastewater treatment, such as bio-sorption, bioaccumulation, and biodegradation, as well as practical applications like fungal bioreactors and microfiltration. Overall, fungal microorganisms offer a promising, eco-friendly, and cost-effective approach to managing wastewater and reducing water pollution.