Fouling is a major challenge in oily wastewater treatment, leading to increased operational costs and reduced membrane performance. This study aims to develop a modified PVDF ultrafiltration (UF) membrane with enhanced antifouling properties using hydrophilic surface-modifying macromolecules (LSMMs) through a simple blending and phase inversion process. PVDF membranes were fabricated by incorporating LSMMs into the dope solution. During phase inversion, LSMMs spontaneously migrated to the membrane-air interface, forming a stable hydrophilic and negatively charged surface layer. The membranes were characterized for their permeability, oil rejection, antifouling performance, and long-term stability under continuous operation. The optimized L0.50 T-PVDF membrane exhibited a 58% increase in pure water flux (880 L m−2 h−1) and 99.9% oil rejection. Irreversible fouling was eliminated (Rir = 0%), with a 100% flux recovery ratio (FRR) sustained over five cleaning cycles. Continuous 24 h filtration maintained a stable permeate flux of 775 L m−2 h−1, indicating excellent durability. LSMM-induced surface modification effectively mitigates membrane fouling by preventing pore blockage and foulant adhesion, eliminating the need for chemical cleaning. This approach offers a sustainable, scalable, and cost-effective solution for industrial oily wastewater treatment. Future work will explore pilot-scale validation, LSMM formulation optimization, and performance evaluation under varied operating conditions.