In this study, zwitterionic polymer poly(sulfobetaine methacrylate) (PSBMA) functionalized graphene oxide (GO) nanocomposites (GO-PSBMA) were synthesized and incorporated into the active layer of a polyamide membrane to improve its water perm-selectivity and fouling-resistant properties. GO-PSBMA nanocomposite contained covalently tethered PSBMA brushes on GO sheets, which were grown by activators regenerated by the electron transfer–atom transfer radical polymerization technique via the “graft-from” strategy. The grafting of zwitterionic PSBMA partially neutralized the surface charge of GO and increased its dispersibility in organic solvent. The incorporation of the GO-PSBMA-1h nanocomposite in the active layer of the polyamide membrane significantly improved surface hydrophilicity of the membrane and reduced its charge density. A near twofold increase in water permeation flux, with the nonsignificant change in MgSO₄ and NaCl rejection, was achieved after the incorporation of 0.3 wt% of GO-PSBMA-1h in the membrane casting solution. With an improved water affinity, the fabricated nanocomposite membrane exhibited a near 80% reduction in bacterial (Escherichia coli) attachment in comparison to the control membrane, even after 48 h of culture. In a crossflow filtration test, the nanocomposite membrane exhibited less of a reduction in the flux associated with bovine serum albumin fouling and salt ion scaling. The results demonstrated that incorporating zwitterionic polymer-decorated GO in the polyamide skin layer is a promising method to fabricate thin film nanocomposite membranes with improved water flux and fouling resistance.