It is highly attractive to design and develop earth-abundant electrocatalysts toward high-efficiency water oxidation electrocatalysis in alkaline media. In this communication, we report the in situ hydrothermal sulfidization preparation of a hierarchical CuCo₂S₄ nanoarray on copper foam (CuCo₂S₄/CF) from its CuCo₂-hydroxide nanowire array precursor. When used as a 3D catalyst electrode for water oxidation, the as-prepared CuCo₂S₄/CF is superior in catalytic activity, demanding overpotentials of only 259 and 295 mV to achieve 60 and 100 mA cm⁻² in 1.0 M KOH, respectively. Moreover, it also shows strong electrochemical durability with high turnover frequency values of 0.069 and 0.390 mol O₂ s⁻¹ at overpotentials of 300 and 400 mV, respectively.