<p>A modified polysulfone (PSF) ultrafiltration (UF) membrane is designed by grafting phytic acid/silver ion (PA-Ag^I) complex aggregates on the membrane surface for achieving improved separation and anti-biofouling performance. We demonstrate that PA molecules directly grafted on the PSF membrane surface through hydrogen bonding offer a suitable coordinating ability to immobilize Ag ions to form hydrophilic aggregates. One-cycle sequential assembly reinforced by a high concentration of PA is confirmed optimal for generating a compact grafting layer with better water affinity and properly narrowing the pore aperture. This modification results in a reasonable permeation flux (313.3&#xa0;L m^–2 h^–1 bar^–1), a high BSA rejection (93.2%) and a good antifouling property. Moreover, the PA-Ag^I/PSF membrane displays excellent antibacterial and anti-adhesion properties against <i>E. coli</i> and <i>B. subtilis</i>, attributed to the gradual release of Ag ions from the moderately stable PA-Ag^I complexes in a favorable aqueous environment. The PA-Ag^I/PSF membrane keeps over 83% of water flux after incubation of bacteria culture for 48&#xa0;h, presenting outperforming anti-biofouling durability. The low dosage of Ag ions from the PA-Ag^I/PSF membrane has merits of low consumption, optimization of release profile, and alleviated environmental concerns.</p>