The synergistic achievement of heteroatom doping, defect engineering and appropriate structural design is efficient to adjust and boost the catalytic performance of catalysts yet challenging. Herein, P-doped NiS₂ hierarchical architectures with sulfur vacancies are synthesized via a Prussian-blue-analogue-sacrificed strategy followed by a phosphidation process. By modulation of phosphorus (P) doping and sulfur vacancies, the optimal catalyst manifests outstanding electrocatalytic activities, affording low overpotentials of 73 mV at 10 mA cm⁻² for hydrogen evolution reaction (HER), and 255 mV at 20 mA cm⁻² for oxygen evolution reaction (OER), respectively. Density functional theory calculations certify that the P dopant not only serves as the new active sites, but also activates the electrochemical activity of neighboring Ni and S sites. Moreover, the synergistcs effect of P-doping with sulfur vacancies further improve electrochemical activities of HER and OER by optimizing the hydrogen (ΔG_H*) and oxygen-containing intermediates (OH*, O* and OOH*) adsorption free energy. This finding provides a directive strategy to design efficient non-noble metal catalysts for energy conversion and storage.