We have investigated the photoluminescence (PL), scintillation and thermally-stimulated luminescence (TSL) dosimeter properties of MgO transparent ceramics doped with different concentrations of Mn²⁺ ion (0.001, 0.01, 0.1 and 1%). The samples were synthesized by a Spark Plasma Sintering (SPS) technique. All the samples show a PL band emission around 730 nm, and the intensity increases with the dopant concentration. The PL decay time constants were a few milliseconds which is on the typical order for Mn²⁺ ion. In contrast, the scintillation spectrum under X-rays shows additional emissions at 340, 620 and 760 nm. After the samples are irradiated by X-rays, the TSL is observed with a main glow peak appearing around 140°C. The TSL response is linearly related to the irradiation dose at least over the dose range from 0.1 to 1000 mGy.