This study reports the preparation and investigations of new ultrafiltration electrospun nanofibrous membranes (ENMs) incorporated with hydrous manganese dioxide (HMO) nanoparticles (NPs) for synthetic oily solution treatment. The mechanical strength and permeation properties of typical polyethersulfone (PES)-based ENMs were enhanced in three highly potential approaches. Firstly, a dimethylformamide (DMF) dope solution was prepared with n-methyl-pyrrolidinone (NMP) as the co-solvent to facilitate inter-fiber junctions. Secondly, HMO NPs were incorporated into the ENM dope solution to enhance water production and anti-fouling resistance against oil molecules. Lastly, the resultant ENMs were subjected to a hot pressing technique (HPT) to strengthen their structure and morphological properties. The results revealed that the ENMs incorporated with HMO NPs exhibited excellent oil rejection (95.42) and promising water flux recovery (82.47) upon exposure to a synthetic oily solution (12,000 ppm). The HMO-incorporated PES ENMs also demonstrated a high clean water productivity of over 3380 L/m2h without sacrificing oil removal rate. Furthermore, they exhibited a low degree of flux decline owing to the improved hydrophilicity and thus reducing oil contamination. This study may serve as a basis for manufacturing high-performance and robust nanocomposite ENMs for heavy wastewater treatment. © 2022 Elsevier Ltd.