A promising new nanocomposite coating based on poly(butyl methacrylate) (poly(BMA)), graphene oxide (GO) and TiO2 nanoparticles (NPs) (i.e., poly(BMA)/GO/TiO2 blend) is reported for magnesium alloy (AZ31) protection in 3.5% NaCl solution. A significant decrease in the corrosion current and a pronounced increase in the charge transfer resistance were observed using poly(BMA)/GO/TiO2 nanocomposite which acted as an excellent passivation layer for ion diffusion and corrosion. The addition of GOto poly(BMA) retarded the corrosive ions diffusion by forming longer and wrapped pathways. Embedding TiO2 NPs into the poly(BMA)/GO coating, resulted in charge transfer blockage at metal/electrolyte interface which suppressed metal dissolution.