Advancing efficient and affordable electrocatalysts to boost the oxygen evolution reaction (OER) is pivotal for sustainable green hydrogen production. Herein, we propose the fabrication of nickel-iron alloy nanoparticles-encapsulated on N-doped vertically aligned graphene array on carbon cloth (NiFe@NVG/CC) as a highly active three-dimensional (3D) catalyst electrode for OER. In 1 M KOH, such NiFe@NVG/CC demonstrates outstanding catalytic performance, necessitating merely overpotential of 245 mV for achieving a current density of 10 mA·cm⁻², a remarkably low Tafel slope of 36.2 mV·dec⁻¹. Furthermore, density functional theory calculations validate that the incorporate of N species into graphene can reinforce the electrocatalytic activity though reducing the reaction energy barrier during the conversion of *O to *OOH intermediates. The outstanding performance and structural benefits of NiFe@NVG/CC offer valuable insights for the development of innovative and efficient electrocatalysts for water oxidation.