Graphene oxide (GO)-doped poly(3,4-ethylenedioxythiophene) (PEDOT) was electrodeposited on 316L stainless steel, and subjected to electrochemical and spectroscopic analyses in 3.5 wt% NaCl aqueous solution. The results show that the introduction of GO in the PEDOT film enhanced its long-term stability and delayed polymer degradation. The GO nanoparticles increased the reactivity of the PEDOT film with dissolved oxygen, thereby increasing the ratio of the oxidized units in the polymer film to enhance conductivity in the NaCl solution. The density functional theory (DFT) calculations reveal that the introduction of GO caused a downward shift in the LUMO energy position and also increased the energy gap of PEDOT. The experimental and computational results agree that GO does not reduce the band gap energy of PEDOT but improves its mechanical properties and redox capacity to enhance the polymer film's barrier protection, stability, and conductivity.