The redox properties and catalytic performance of Ce_1−xZr_xO₂ (0 ≤ x ≤ 0.2) nanorods, mainly exposing {110} and {100} planes, were comparatively examined with spherical Ce_1−xZr_xO₂ nanoparticles that predominantly exposed {111} planes. The CeO₂ nanorods had a superior redox property and much higher activity towards CO oxidation than the CeO₂ nanoparticles, primarily because of the preferential exposure of the reactive {110} planes. However, this shape effect was weakened considerably in Ce_1−xZr_xO₂ (x = 0.05–0.20) nanomaterials. ZrO₂-doping promoted the reducibility of the nanoparticles more signifciantly than that of the nanorods, involving different rate-determining steps in the reduction process. The activity for CO oxidation enhanced with increasing ZrO₂ content on the nanoparticles but decreased over the nanorods. These results demonstrate that the shape effect of Ce_1−xZr_xO₂ nanomaterials is associated with the amount of zirconia that is incorporated into the ceria lattice.