Phosphors are efficient luminescent materials that are being extensively used in lighting and displays in today's world. However, the serious emission loss at high temperatures due to thermal quenching effects is still one of the most significant challenges that limit the application of phosphors. Herein, we report a unique thermal sensitizing effect of the Na₂CaGe₆O₁₄:Pr³⁺ phosphor, in which the red emission of Pr³⁺ is significantly enhanced with the increase in temperature, even upto 250 °C. Moreover, the emission of the phosphor still keeps increasing over time at high temperatures. This thermally induced emission increase originates from the generation of more defect levels and more efficient energy transfer from the defects to Pr³⁺ at higher temperatures. This significant discovery may enlighten a new strategy to minimize or even completely eliminate the serious thermally induced emission loss of the phosphors.