<p>Laser cladding technology is an efficient method for repairing downhole drilling tools. The microstructural evolution and tribo-corrosion mechanism of Ni-WC laser-clad coating were investigated. The microstructural results indicate that the Ni-WC laser-clad coating is mainly composed of γ-Ni, WC, W₂C, M_xC_y (M = W, Ni, Cr, Fe, Mo), M₂₃C₆ (M = W, Ni, Cr, Fe, Mo), and eutectic phases (CrC / MoC). Cl⁻ exacerbates the corrosion of M_xC_y layer around WC particles by penetrating cracks, which further causes the shedding of the M_xC_y layer during wear. During tribo-corrosion, the Ni-WC laser-clad coating’s open-circuit potential shifts negatively with increasing loads. Meanwhile, <i>E</i>_corr shifted negatively and <i>I</i>_corr gradually increased, indicating more severe corrosion promoted by wear. The wear rate of coating is higher under open-circuit potential compared to that under pure mechanical wear, and mechanical wear is predominant in tribo-corrosion.</p> Graphical abstract <p></p>