Membrane technology has been deployed in wastewater treatment and downstream processes in various industrial applications. Recently, electrospun nanofibrous membranes (ENMs) have gained interest due to their broad range of filtration applications owing to interconnected pore structure, high surface area as well as porosity, and ease of functionalization. This chapter provides a comprehensive review of ENMs on the novel applications for both pressure-driven and osmotically driven membrane separation processes. The study primarily outlines the principles of membrane separation processes. The significance of functionalized ENMs is discussed by their application for desalination, wastewater treatment, and bioseparation via ultrafiltration (UF), nanofiltration (NF), forward osmosis (FO), and reverse osmosis (RO). ENMs fouling is also discussed in the individual membrane separation process. The challenges of ENMs for industrial-scale applications are also addressed. Overall, this study would provide a hint on the recent development of ENMs in water treatment and bioseparation applications.