This work reports on a new morphology-inheriting methodology to MgO nanoplates. Precursor of Mg(OH)2 nanoplates was synthesized by a solvothermal method and showed a hexagonal shape. The morphological features of Mg(OH)2 nanoplates were retained to the resulting MgO nanoplates using a programmed heating process. MgO nanoplates showed highly hydroxylated surfaces. Upon excitation, the interactions between hydroxyl groups and surface O2−4c and O2−3c species gave rise to a dominant ultraviolet emission at 415 nm.