Graphene oxide (GO) has been applied for membrane-based oil/water emulsion separation processes due to its ease of functionalization, substantial surface area, and abundant hydrophilic hydroxyl and carboxyl functional groups. In this study, the dispersion of GO in polyamide 6 (PA6) was improved through grafting of GO with polyethylene glycol (PEG). The prepared GO-PEG was integrated into PA6 nanofibers at different loading levels and the oil/water emulsion separation of the resulting PA6/GO-PEG membranes was compared as a function of GO-PEG content. The homogeneous dispersion of GO-PEG at a 2 wt% loading level within PA6 nanofibers (designated as PA6/GO-PEG2) resulted in a nanofibrous composite membrane that exhibited exceptional mechanical strength (approximately 16.29 MPa), and remarkable hydrophilic properties (water contact angle of 12.30°). Moreover, a remarkable underwater superoleophobicity was exhibited by PA6/GO-PEG2 and provided an underwater oil contact angle of 150.41°. Notably, the optimal characteristics were showcased by the PA6/GO-PEG2 nanofibrous membrane, offering an impressive water flux rate of 813 L/m2h and an outstanding oil rejection efficiency of 99.26 % when subjected to an oil/water emulsion under a pressure of 1 bar. Furthermore, robust antifouling properties were displayed by PA6/GO-PEG2, in which 95.69 % of the water flux rate was maintained and reached 778 L/m2h, and excellent oil rejection efficiency remained at 98.59 % even after 15 cycles of oil/water separation. These results highlight the potential of the PA6/GO-PEG2 nanofibrous membrane as a highly promising candidate for practical applications in oil/water separation, owing to its superior performance and enduring antifouling characteristics.