A hollow microtube–nanowire structure of carbon-doped ZnO was fabricated via using carbon fibers as the sacrificed substrates. The hollow microtube–nanowire architecture was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman, photoluminescence and electrical measurements. The results indicate that carbon is self-doped into ZnO primarily substituting oxygen in the growth and annealing processes. The room temperature photoluminescence spectrum of the carbon-doped ZnO shows a strong defect-induced emission in the visible range of 400–800 nm. The optoelectronic properties in the range of the visible light are demonstrated by operating an organic/inorganic p–n heterojunction and a metal–semiconductor–metal (M–S–M) structure, which indicates that carbon doping in ZnO extends its photoelectric specifics in the visible light region.