Chitosan-functionalized graphene oxide (CS-GO) was synthesized and incorporated into a poly(vinylidene fluoride) (PVDF) ultrafiltration membrane. The effect of CS-GO addition on the morphology and membrane performance was studied through water contact angle, scanning electron microscopy, atomic force microscopy, porosity, pore size, and permeation measurements as well as rejection tests and antifouling experiments. The CS-GO/PVDF membrane exhibited higher water flux, bovine serum albumin (BSA) rejection rate, and water flux recovery ratio, and lower BSA solution flux attenuation rate than those of unfilled PVDF, CS/PVDF, and GO/PVDF membranes. The excellent water permeability and antifouling performance can be attributed to the high hydrophilicity and good dispersion of CS-GO in the matrix.