Metal corrosion and biological fouling are the two major problems that plague metal applications, and epoxy composite coatings with the high-efficiency corrosion protection and antifouling agents are gradually applied in industrial fields. The poly(aniline-co-nitroaniline) (CPANOA) nanoparticles were prepared by the simple oxidative copolymerization of nitroaniline and aniline monomers, which improved the dispersion, affinity with metals, and antibiotic activities of polyaniline (PANT) nanowires, and characterized by scanning electron microscopy, Fourier transform infrared, UV-vis absorption spectra, wettability test, cyclic voltammetry, and thermogravimetric analysis. The antibacterial and antifouling tests were employed to investigate the antifouling performance of CPANOA nanoparticles in the epoxy coatings, and the electrochemical impedance spectroscopy results demonstrated that the corrosion resistance of the composite coatings with CPANOA nanoparticles is equivalent to that of the epoxy coatings with PANI nanowires, which provides the basis for realizing the integrated function of antifouling and corrosion protection of organic coatings.