CeO₂ nanobelts, nanorods and nanowires have been synthesized by a formaldehyde-assisted hydrothermal system. It is found that the morphologies of these one-dimensional (1D) CeO₂ nanomaterials are dependent on the components of the corresponding precursors, which is achieved to control the reaction degree of Cannizzaro disproportionation tuned by Na/Ce molar ratio, hydrothermal temperature and type of strong alkali. The characterization results indicate that the morphologies of 1D CeO₂ nanomaterials are closely correlated to their structural features, such as lattice cell parameters, specific surface area and pore volume. These 1D nanomaterials show excellent morphology-dependent optical absorption and catalytic performance. From nanowires, nanorods to nanobelts, the visible absorption gradually decreases along with the increasing of band gap values, whereas the catalytic activity of CO oxidation increases along with lattice cell expansion. This synthetic route using formaldehyde may open a new insight into fabricating one-dimentional rare earth oxides with different morphologies and extending their potential applications.