A series of ultrafiltration (UF) membranes based on polysulfone and mussel-inspired poly(dopamine methacrylamide) (PDMA) were prepared by an in-situ process composed of grafting-through approach and consecutive non-solvent induced phase separation. Nisin, a low molecular weight antimicrobial peptide, was subsequently immobilized on the surface of the UF membrane through the reaction between the NH2 groups of nisin and catechol groups of PDMA moiety in the membrane. The resulting nisin containing UF membranes showed outstanding fouling resistance and flux recovery ability due to the hydrophilic characteristics of the PDMA moiety, and also exhibited antimicrobial activity against the Staphylococcus aureus (ATCC 6538) due to the nisin moiety.