With the objective of developing anticorrosive conductive polymeric coatings to combat microbially induced corrosion (MIC), a facile and green synthesis approach based on a thermally induced reaction was described. Thermal curing of polyaniline (PANI) was carried out from the silanized mild steel (MS) surface containing reactive epoxy groups, followed by thermally induced N-alkylation of PANI by hydrophobic 4-vinylbenzyl chloride (VBzCl) to produce biocidal functionality. The so-synthesized MS coupons with hydrophobic poly(vinylbenzyl chloride) (PVBC)-quaternized PANI bilayer coatings were investigated for their anticorrosive and antibacterial properties toward biocorrosion induced by sulfate-reducing bacteria (SRB). Antibacterial assay results revealed an evident decrease in the bacterial attachment and the formation of biofilm. The QPANI-PVBC bilayer coatings showed a high corrosion resistance (inhibition efficiency >97%) and stability to resist SRB-induced corrosion. Thus, the QPANI-PVBC bilayer coated MS substrates can be used as effective polymeric coatings to protect the steel-based equipment in corrosive marine environments.