Magnesium alloys have been broadly used due to their lightweight and high ductility. However, they are subject to corrosion which deteriorates their properties. To develop a novel corrosion inhibitor coating for Mg alloys, we performed functionalization of a graphene oxide (GO) matrix with Tb(iii) to improve the electrochemical behaviour and coating stability of a GO and Tb composite on the metal alloys in corrosive medium. The functionalized terbium GO material was characterized by microscopy, spectroscopy, and XRD techniques to confirm the non-covalent interactions on the active surface of the host material. The corrosion inhibition was found to be ca. 80% and electrochemical stability was observed to be high at a voltage of 900 mV. Computational studies also support the potential anti-corrosion applications of this material.