<p>304 stainless steel is widely used in marine engineering applications but is highly susceptible to corrosion caused by environmental ions. Conventional epoxy resin coatings fail to provide long-term protection for its surface. To address the aforementioned issue, zirconium dioxide-multi-walled carbon nanotube (ZrO₂-MWCNTs) nanohybrid materials were prepared via the sol–gel method and incorporated into epoxy coatings to enhance the anti-corrosion performance of epoxy resin coatings. The results of structure and morphology confirmed that the ZrO₂ was successfully grafted onto the surface of the MWCNTs and significantly enhancing the dispersion of the carbon nanotubes, which is helpful to the formation of more compact coating. Then, the epoxy composite coatings with varying concentrations of ZrO₂-MWCNTs (0.2 wt%, 0.4 wt%, 0.6 wt%) were fabricated, and the effect of the hybrid fillers on corrosion resistance was evaluated through analyses of micromorphology, surface hydrophobicity, potential polarization, and electrochemical impedance spectroscopy (EIS). Among all the coatings, 0.4 wt% ZrO₂-MWCNTs exhibited the best corrosion resistance, as evidenced by its lowest polarization current density and highest charge transfer resistance. During corrosion, aggressive species such as H₂O, O₂, Na⁺, and Cl⁻ penetrate coating defects and reach the substrate surface, initiating metal corrosion. The ZrO₂-MWCNT composite effectively fills the coating’s pores, increasing its compactness and activating a synergistic “conductivity-shielding-adsorption” anticorrosion mechanism, thereby significantly enhancing its protective performance. This research provides a foundation for the reliable service of marine engineering equipment and facilities and holds significant value for the advancement of metal corrosion protection coatings.</p> Graphical Abstract <p></p>