Corrosion protection of mild steel by a newly developed chlorinated rubber (CR)-based coating system containing the inherently conductive polymer polyaniline (PAni) as an anticorrosion agent was studied. The synthesis of PAni and preparation of CR-based paint containing this polymer are described herein. The corrosion behavior of mild steel samples coated with a CR resin, CR/PAni-EB (emeraldine base), CR/PAni-ES (emeraldine salt), and CR/DBSA-doped PAni were investigated in 3.5% NaCl solution. For this purpose, electrochemical impedance spectroscopy and corrosion potential versus time measurements were utilized. It was found that the addition of the two forms of PAni, doped and undoped, to the CR resin increased its corrosion protection efficiency.