This study reports the preparation of nanostructured cerium-doped titanium dioxide photocatalysts containing different cerium concentrations by a modified sol-gel route involving the use of acetylacetone. The nanocrystalline powders had their structural, morphological, and optical properties characterized by X-ray diffraction, vibrational and Raman spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, Brunauer, Emmett and Teller (BET) surface area analysis, scanning electron microscopy combined with energy dispersive X-ray spectroscopy, total reflection X-ray fluorescence, and diffuse reflectance spectroscopy. Cerium incorporation reduced the bandgap energy of the solids to values that allowed them to absorb visible light. Cerium presence improved the textural properties that are crucial for the catalytic process. The photocatalytic activities were evaluated through photodegradation experiments of methyl orange dye solution. The synthesis with acetylacetone as stabilizer provided nanostructured materials with higher Ce3+/Ce4+ ratio, which enhanced the photocatalytic activity. Smaller quantities of the doped photocatalysts afforded higher degradation rates than the rates reported in the literature.