Ce-doped bismuth oxybromide (BiOBr) nanoplates were successfully synthesized by a facile hydrothermal method. The phase, composition, chemical state, microstructures, spectrum response, band gap, electron transfer and photocatalytic activity were analyzed in detail by a series of advanced tools. The results indicated that Ce3+ ions were successfully incorporated into the crystal lattice of BiOBr. With the increase of Ce-doped amounts, the morphology gradually changed from nanowalls to nanoplates. Moreover, introducing Ce3+ ions into BiOBr crystal not only slightly blue-shifed the adsorption edge, but also slightly widened the band gap. Compared to pure BiOBr, Ce-doped samples exhibited enhanced photocatalytic activity towards Rhodamine B (RhB) degradation under visible-light irradiation. The enhanced performance may result from higher specific surface area, faster charge transfer and lower carrier recombination. This works further reveal the mechanism of enhanced photocatalytic activity about rare-earth doped photocatalysts.