This chapter delves into the practical applications of fungi in wastewater treatment. Focusing on real-world case studies, it highlights the roles of various fungal phyla—Ascomycetes, Basidiomycetes, Zygomycetes, Yeasts, and Filamentous Fungi—in bioremediation processes. The chapter discusses their mechanisms of action, including enzymatic degradation, biosorption, and bioaccumulation, and showcases their effectiveness in removing contaminants like heavy metals, organic pollutants, and pharmaceuticals from wastewater. Additionally, it addresses the advantages of fungal treatment, such as cost-effectiveness and sustainability, while also acknowledging challenges related to scalability and operational limitations. The insights provided aim to reinforce the potential of fungi as a viable solution for sustainable wastewater management.