Abstract The zwitterionic phosphorylcholine polymer was covalently grafted on a polyamide reverse osmosis (RO) membrane for anti-biofouling, using surface-initiated atom transfer radical polymerization (ATRP). Polyamide RO membranes modified with hydroxyl groups of diethanolamine (DEA) were fabricated by interfacial polymerization. The ATRP initiator, 2-bromoisobutyryl bromide (BIBB), was immobilized on the fabricated membrane, by condensation between DEA hydroxyl groups and BIBB carboxylic bromide. BIBB immobilization was confirmed by X-ray photoelectron spectroscopy. ATRP was carried out using 2-methacryloyloxyethyl phosphorylcholine (MPC) and immobilized BIBB. Attenuated total reflectance Fourier transform infrared spectra indicated that the MPC polymer was grafted on the membrane surface. The amount of grafted MPC polymer increased with increasing polymerization time. The surface morphology of the MPC polymer-grafted membranes became smoother with increasing polymerization time. The polyamide RO membrane with grafted MPC polymer retained its initial water flux in a crossflow bacterial filtration test, preventing bacterial adhesion on the surface.