Palladium (Pd) is regarded as one of the most active catalysts for electrochemical ethylene glycol oxidation reaction (EGOR) to value-added glycolate, but its large-scale application is still restricted by limited catalytic effectiveness and exorbitant cost. Herein, we designed and synthesized the defect-rich nickel sulfide nanosheet arrays on nickel foam (Ni_3−xCo_xS₂@NF) as the self-supported substrate to anchor well-dispersive Pd nanoparticles (Pd-Ni_3−xCo_xS₂@NF) with its loading as low as approximately 3.03 wt.%, which is conducive to the exposure and utilization of the active Pd sites. The optimal Pd-Ni_3−xCo_xS₂@NF electrocatalyst (1 cm² working area) could achieve an efficient EGOR performance, showing a current density of 100 mA·cm⁻² at 0.77 V vs. reversible hydrogen electrode (RHE), and 98.1% Faradaic efficiency of glycolate. Furthermore, the in-situ Raman spectra reveal that the interaction between Pd and Ni_3−xCo_xS₂@NF significantly increases the adsorption of EG, and Ni_3−xCo_xS₂@NF enhances the *OH adsorption capacity, thus further improving the EGOR activity and stability. This study provides an effective paradigm for enhancing the utilization and electrocatalytic performance of noble metallic catalysts, and also offers a deep insight into the interaction between the active sites and substrate.