Abstract The study focused on investigating the fouling propensity of polysulfone (PSF) hollow fiber (HF) mixed matrix membranes modified with 1.0 wt % graphene oxide (GO). Through a comprehensive set of analyses including scanning electron microscopy (SEM), atomic force microscopy (AFM), water contact angle (WCA), and mechanical assessments, the structural characteristics and properties of both untreated and GO‐modified PSF HF membranes were thoroughly examined. The scope of evaluation encompassed filtration and separation experiments involving not only pure water but also a range of model contaminants with distinct sizes, such as bovine serum albumin (BSA), humic acid (HA), E. coli bacteria, and oil‐in‐water emulsion. Remarkably, the incorporation of graphene oxide (GO) into the PSF HF membranes led to a substantial enhancement in their antifouling performance. The GO‐modified membranes exhibited an impressive recovery rate of over 90 % of their initial pure water flux during filtration experiments involving humic acid (HA) and oil, demonstrating their exceptional resistance to irreversible fouling. Moreover, the GO‐modified membranes exhibited superior oil separation efficiency, further underscoring their efficacy in real‐world separation applications. It is noteworthy that the fouling parameters in the case of bovine serum albumin (BSA) were relatively similar for both the unmodified and GO‐modified PSF HF membranes. This observation suggests that the introduction of graphene oxide might not significantly influence the interaction between the membrane and BSA molecules. Interestingly, while both types of PSF HF membranes displayed high retention capabilities for E. coli bacteria, the addition of graphene oxide did not result in any noticeable improvement in this regard.