A novel strategy by combination of surface-initiated atom transfer radical polymerization (ATRP) and in situ chemical oxidative graft polymerization was employed to tether stainless steel (SS) with poly(4-vinylaniline)-polyaniline (PVAn-PANI) bilayer coatings for mitigating biocorrosion by sulfate reducing bacteria (SRB) in seawater. A trichlorosilane coupling agent was first immobilized on the SS surfaces to provide sulfonyl. halide,groups for surface initiated ATRP of 4-VAn. A subsequent grafting of PANT onto the PVAn-grafted surface was accomplished by in situ chemical oxidative graft polymerization of aniline. The PVAn-PANI bilayer coatings were finally quaternized by hexylbromide to generate biocidal functionality. The so synthesized SS surface Was found to significantly reduce bacterial adhesion and biofilm formation. Electrochemical results revealed that the PVAn-PANI modified SS surface,exhibited high resistance to biocorrosion by SRB. With the inherent anticorrosion capability and antibacterial properties of quaternized PVAn-PANI bilayers, the functionalized SS substrates are potentially useful to steel based equipment under harsh marine environments.