We demonstrate the synthesis of new Cu–Si1−x Ge x core–shell nanowire array electrodes by directly depositing Si1−x Ge x layer on the surface of pre-synthesized Cu nanowire arrays via co-sputtering method. When used as anodes of lithium-ion batteries, the Cu–Si1−x Ge x (x =0.4) nanowire array electrodes show excellent electrochemical performance in terms of cycle stability and rate capability, which is much better than that of planar electrodes. The improved performance can be attributed to the good strain accommodation, fast electron transport and good electrical contact of the nanowire array electrodes. The effect of Ge content and the thickness of alloy film on the electrochemical performance of the three-dimensional electrodes have also been investigated.