Hybrid ZnO-graphene nanoparticles (ZnO-Gr NPs, 20 nm) were used as fillers to create thin film nanocomposite membrane (TFN) by interfacial polymerization of m-phenylenediamine (MPD) and trimesoyl chloride (TMC) monomers on a porous support. The prepared membranes were characterized via scanning electron microscopy (SEM), transmission electron microscopy (TEM), contact angle measurement, and attenuated total reflection Fourier transform infrared (ATR FT-IR) analysis. Result showed that the water flux and salt rejection increased with increasing concentration of NPs. Furthermore, the modified membrane showed excellent fouling resistance. Comparison of membrane performance with those prepared by embedding ZnO NPs (100 nm) and graphene oxide (GO, 200 to 500 nm) exhibited that small size NPs could improve water flux and fouling resistance without sacrificing salt rejection.