Metallic doping effectively extends the light response range of TiO2 photocatalysts from the ultraviolet (UV) to the visible region. We prepared Ce-doped TiO2 nanotubes (Ce-TiO2 NTs) using a sol-gel process followed by a hydrothermal treatment. The Ce-TiO2 NTs were characterized by X-ray diffraction, transmission electron microscopy, Brunauer-Emmett-Teller surface area, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), and photoluminescence (PL) spectroscopy. Given that the optical absorption was extended to wavelengths of 600 nm, the Ce-TiO2 NTs demonstrated excellent photocatalytic activity for degrading methylene blue under visible light irradiation. Ce-TiO2 NTs with various amounts of Ce doping (0.06-0.40 g of cerium nitrate hexahydrate added during preparation) were tested, and the 0.12Ce-TiO2 NTs showed the highest photocatalytic activity, 7 times higher than that of P25. For their efficient photodegrading of dyes under visible light, these Ce-TiO2 NTs may be useful for waste water treatment.