Large aspect ratio single crystalline cobalt antimony (CoSb) nanowire arrays were synthesized by a pulsed electrodeposition technique. X-ray diffraction analysis showed that the as-synthesized nanowires have a highly preferential orientation. Scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy indicate that high-filling, ordered, and single-crystalline nanowires were obtained. Energy dispersive spectrometry analysis shows that the atomic ratio of Co to Sb is very close to 1:1, and the growth mechanism and the electrodeposition process are below discussed, together with a chemical composition analysis. The electrochemical performance shows that the discharge capacity is very high for the CoSb nanowire/AAM electrodes, and the electrodes exhibit better capacity retention than the pure metal Sb electrodes.