Overcoming the increased protein fouling of polymeric polyethersulfone-based membranes (e.g. PES-PVP, PES-pluronic, and PES-Tetronic) is an essential target for wider ulrafiltration-based applications of such fabricated membranes. Hence, this study has been actively devoted to trace both performance and characteristics changes of modified PES-based membranes upon exposure to harsh cleaning condition by sodium hypochlorite (400 ppm for 10 days). Simultaneously, different characterization tools have been adopted to study such purpose such as SEM, FTIR, tensile strength, performance patterns. SEM analysis has proved the increment in pore size after contacting the fabricated membranes with NaOCl agent. However, tensile strength, contact angle, and overall porosity criteria showed a slight change. For instance, overall porosity ranged between 70-80 %, contact angle difference was about 3-4 deg, and tensile strength decrement was negligible. Further, AFM data proved that the relative roughness of all membranes did not dramatically. what is more, performance patterns in terms of pure water permeability is boosted two-three fold compared to untreated membranes with preserving BSA rejection ability (e.g. maximum BSA rejection loss is recorded for PES-T904 membrane; decrease from 70 % to about 55 %; about 21 % loss). Such preserved ultrafiltration behaviour may be ascribed to the more formed negative charge, and preservation hydrophilic nature even after NaOCl exposure. to end with, the fabricated modified PES membranes showed a preserved ultrafiltration performance after such harsh cleaning condition.