Abstract: Proton-exchange membrane water electrolysis (PEM WE) is a particularly promising technology for renewable hydrogen production. However, the excessive passivation of the gas diffusion layer (GDL) will seriously affect the high surface-contact resistance and result in energy losses. Thus, a mechanism for improving the conductivity and interface stability of the GDL is an urgent issue. In this work, we have prepared a hydrophilic and corrosion resistant conductive composite protective coating. The polydopamine (PDA) film on the Ti surface, which was obtained via the solution oxidation method, ensured that neither micropores nor pinholes existed in the final hybrid coatings. In-situ reduced gold nanoparticles (AuNPs) improved the conductivity to achieve the desired interfacial contact resistance and further enhanced the corrosion resistance. The surface composition of the treated samples was investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results indicated that the optimized reaction conditions included a pH value of 3 of HAuCl₄ solution with PDA deposition (48 h) on papers and revealed the lowest contact resistance (0.5 mΩ·cm²) and corrosion resistance (0.001 µA·cm⁻²) in a 0.5 M H₂SO₄ + 2 ppm F⁻ solution (1.7 V vs. RHE) among all the modified specimens, where RHE represents reversible hydrogen electrode. These findings indicated that the Au–PDA coating is very appropriate for the modification of Ti GDLs in PEM WE systems.