NiCo₂O₄ has been proved to be a promising electrochemical material. In this work, a hollow NiCo₂O₄ material with an urchin-like structure is constructed by a self-template of Ni–Co complex compound based on the Ostwald ripening mechanism. During the thermal annealing in air, the residual carbon from the organic ligands of the Ni–Co complex compound leads to the generation of oxygen vacancies in urchin-like NiCo₂O₄. The as-obtained hollow NiCo₂O₄ (H-NiCo₂O₄-12) material manifests admirable specific capacitance of 886 F g⁻¹ at 1 A g⁻¹ and preserves 80% of capacitance retention after 5000 cycles. Moreover, the assembled asymmetric supercapacitor of H-NiCo₂O₄-12//AC delivers an energy density of 33.4 W h kg⁻¹ at 747.7 W kg⁻¹ and a high coulombic efficiency of about 95%. The improved supercapacitive performance of H-NiCo₂O₄-12 is attributed to its synergistic effect of hollow structure and oxygen vacancies. The hollow urchin-like structure of NiCo₂O₄ can buffer the volume expansion, expose abundant reaction active sites, and favor the transport of ions; while oxygen vacancies can adjust the electronic structure of NiCo₂O₄, which can favor the transfer of electrons. This work may throw some light on designing a virtue supercapacitor electrode material with hollow nanoporous morphology.