Energy crises, environmental pollution, and freshwater deficiency are critical issues on the planet. Electrolytic hydrogen generation from saline water, particularly from salt-contained hazardous wastewater, is significant to both environment and energy concerns but still challenging due to the high energy cost, severe corrosion, and the absence of competent electrocatalysts. Herein, a novel strategy is proposed for energy-efficient hydrogen production coupled with electro-oxidation removal of ethanolamine pollutant in saline water. To achieve this, an active and durable heterostructured electrocatalyst is developed by in situ growing Ni@Ni₃S₂ core@shell nanoparticles in cross-linked 3D carbon nanotubes’ (CNTs) network, achieving high dispersibility and metallic property, low packing density, and enriched exposed active sites to facilitate fast electron/mass diffusion. The unique Ni@Ni₃S₂/CNTs nano-heterostructures are competent for long-term stably electro-oxidizing environmental-unfriendly ethanolamine at a high current density of 100 mA cm⁻² in saline water, which not only suppresses oxygen and chloride evolution reactions but also decreases the energy consumption to boost hydrogen production. Associated with experimental results, density functional theory studies indicate that the collaborative adsorption of electrolyte ions and ethanolamine molecules can synergistically modulate the adsorption/desorption properties of catalytic active centers on Ni@Ni₃S₂/CNTs surface, leading to long-term stabilized electrocatalysis for efficient ethanolamine oxidation removal and less-energy hydrogen simultaneous production in saline water.