We report the synthesis of mixed Ni–Cu-oxide nanowire array on flexible metal substrate by a hydrothermal process and subsequent decomposition-related annealing treatment. Every single nanowire is a particles matrix with embedded NiO and CuO grains. To the best of our knowledge, this is the first report that mixed oxides exist in this aligned architecture. As an example of the functional properties of the compound materials, the mixed Ni–Cu-oxide nanowire array is investigated as the additive-free electrode for enzyme-free glucose sensor. Compared with previously reported Ni or Cu-contained biosensors, this Ni–Cu–oxide array electrode possesses higher performance. The detection limit can be as low as 0.1 μM, linear range as wide as 0.1–1200 μM and sensitivity as high as ∼1600 μA mM⁻¹ cm⁻². Besides the above, other excellent properties such as anti-interferences and long-term stability, are demonstrated as well. All these improvements can be attributed to the synergetic effect between the mixed oxide grains and the unique 1D array feature.