In this study, a milled carbon nanofiber-reinforced composite paint was prepared to enhance the anti-corrosive properties of concrete structures. Shorter-length (40 μm) milled carbon fibers (MCFs) showed an increased viscosity relative to longer MCFs (120 μm) owing to their 2 weeks (the decrease was especially strong in the acid solution). A carbon nanotube (CNT)- reinforced composite paint showed similar results in uniform distribution in the epoxy resin. The latter showed a decrease in viscosity owing to agglomerative movement in the epoxy resin. The surface hardness and tensile strength of the composite paint linearly increased as the carbon nanofiber loading was increased by up to 7.2 wt% in the epoxy resin, and slowly decreased after soaking in a sulfuric acid or sodium hydroxide solution for to those of the MCFs, whereas CNTs dispersed in isopropyl alcohol (IPA) in advance and mixed with resin showed lower hardness values than those without dispersion in IPA at the same loading. The mechanical properties such as the Shore D hardness and tensile strength of the MCF-reinforced composite paint increased significantly, resulting in a slower surface degradation of the composite paint concrete in a sulfuric acid and sodium hydroxide solution.