Recently, graphene-filled polymeric composites have been utilized for achieving durable active corrosion protection properties in seawater solutions. The utilization of reduced graphene oxide (rGO) is highly recommended for this purpose. Although the traditional reductants can successfully reduce the GO layers, employing green active agents is far more affordable. In the present study, Mustard seed extract was introduced as a novel cost-effective, and green reductant for GO layers since it includes active agents like arabinose, allyl isothiocyanate, galactose, xylose, diallyl trisulfide, and rhamnose molecules. For boosting the active protection property, the rGO nano-sheets were doped with Zn (II) ions (Zn@rGO) as the inorganic inhibitor. The synthesized nanosheets' anti-corrosion impacts in the solution phase were illustrated by polarization and EIS techniques. The obtained results have proved that the Zn@rGO containing saline solution exposed steel samples resulted in 88% degree of inhibition in mixed mode. The EIS assessments carried out over the scratched epoxy composite reflected that the coating resistance was raised from 12,491 Ω cm2 to 47,480 Ω cm2, affirming the inhibitive corrosion prevention potency of the Zn@rGO/EP composite. The FE-SEM captures have displayed that the inhibitive layer filled the scratched zones successfully. Besides, the intact coating's high resistance (over 30 GΩ.cm2) indicated that the constructed nano-filler could effectively promote the EP coating barrier index. The optical captures after conducting a salt-spray test have demonstrated that after the EP anti-corrosion performance was significantly improved in the presence of Zn@rGO nano-layers. The coating delamination diameter reduction from 28 mm for the neat epoxy to 11 mm for the Zn@rGO loaded coating was recorded in the cathodic disbondment test. In addition, the theoretical findings ensured the affinity of the zinc ions/ME compounds for adsorption on the GO layers.