Alumina nanoparticles were decorated with poly(acrylic acid) (PAA) as a hydrophilic polymer by thermal polymerization of acrylic acid in the presence of alumina nanoparticles. The obtained PAA-decorated alumina (PAA-d-Al) nanoparticles were embedded in the polysulfone membrane matrix via nanofiller dispersion in the casting solution. The prepared membranes were characterized by porosity and water contact angle measurements, scanning electron and atomic force microscopy, and fouling tests using whey proteins. The presence of nanoparticles had significant effects on the membrane hydrophilicity and surface softness, resulting in fouling mitigation and flux recovery enhancement compared with the virgin polysulfone membrane. Moreover, the prepared membrane embedded with 0.25 wt % of PAA-d-Al nanofillers showed a remarkable durability and reusability during the filtration tests.