We report a single-crystalline Co₃O₄ nanowire array grown on a nickel foam prepared by a hydrothermal synthesis method for supercapacitor application. The Co₃O₄ nanowires show sharp tips and have an average diameter of 70 nm, and a length up to 25 μm. Impressively, the as-prepared single-crystalline Co₃O₄ nanowire array exhibits noticeable pseudocapacitive performance with a high capacitance of 754 F g⁻¹ at 2 A g⁻¹ and 610 F g⁻¹ at 40 A g⁻¹ as well as excellent cycling stability. The enhanced supercapacitor performance is due to the unique one-dimensional (1D) architecture, which provides fast diffusion paths for ions and facilitates the electron and ion transfer on the Co₃O₄/electrolyte interfaces. Moreover, the 1D nanowire array can accommodate the volume expansion and restrain the pulverization and deterioration of Co₃O₄ during the repeated cycling process, resulting in enhanced cycling stability.