Nitrate (NO₃⁻) contamination in water adversely affects human health and the ecosystem. Electrochemical methods can remediate environmental NO₃⁻ pollution. This study developed Ru-Cu₂O/Co₃O₄@copper foam (CF), a hierarchical catalyst comprising a CF substrate, Cu-Co layered double hydroxide (LDH) nanosheets, and ultrasmall Ru nanoparticles. Traditional characterization confirmed its active component composition and chemical oxidation states. Studies on electrochemical NO₃⁻ reduction have evaluated catalytic efficacy under various conditions. This catalyst exhibits exceptional efficacy in NO₃⁻ catalysis. At −1.61 V vs. Ag/AgCl, it converts 50 mg/L NO₃⁻–N into pure, environmentally friendly N₂ after 4 h, achieving a 98.44% removal efficiency and approximately 100% selectivity, enabling efficient NO₃⁻ elimination and green N conversion. Throughout 20 cycles, the removal rate of NO₃⁻–N remained consistently high (94.19%–99.53%), whereas N₂ selectivity exhibited excellent stability (93.62%–100%).