Black-colored ZnO nanowires have been prepared in a metal-organic chemical vapor deposition system by employing a relatively low growth temperature and oxygen-deficient conditions. X-ray photoelectron spectroscopy reveals the incorporation of carbon into the nanowires. The photocatalytic hydrogen evolution activity of the black-colored ZnO nanowires is over 2.5 times larger than that of the pristine ZnO nanowires under simulated solar illumination conditions, and the enhanced photocatalytic activity can be attributed to the higher absorption of visible light by the black color and better carrier separation at the ZnO/carbon interface.