Although being applied in various fields, white light emitting diodes (WLEDs) still have drawbacks that urgently need to be conquered: the luminescent intensity of commercial phosphors sharply decreases at working temperature. In this study, we calculated the forming energy of defects and confirmed that the V Na defect state can stably exist in β-NaGdF 4 , by density functional theory (DFT) calculation. Furthermore, we predicted that the V Na vacancies would provide a zero thermal quenching (ZTQ) property for the β-NaGdF 4based red-light phosphor. Then, a series of β-NaGdF 4 :xEu 3+ and β-NaGdF 4 :0.25Eu 3+ ,yYb 3+ red-light phosphors were synthesized by the hydrothermal method. We found that β-NaGdF 4 :0.25Eu 3+ and β-NaGdF 4 :0.25Eu 3+ ,0.005Yb 3+ phosphors possess ZTQ properties at a temperature range between 303−483 K and 303−523 K, respectively. The thermoluminescence (TL) spectra were employed to calculate the depth and density of the V Na vacancies in β-NaGdF 4 :0.25Eu 3+ and β-NaGdF 4 :0.25Eu 3+ ,0.005Yb 3+ . Combining the DFT calculation with characterization results of TL spectra, it is concluded that electrons stored in V Na vacancies are excited to the exited state of Eu 3+ to compensate for the loss of Eu 3+ luminescent intensity. This will lead to an increase of luminescent intensity at high temperatures and facilitate the samples to improve ZTQ properties. WLEDs were obtained with CRI = 83.0, 81.6 and CCT = 5393, 5149 K, respectively, when phosphors of β-NaGdF 4 :0.25Eu 3+ and β-NaGdF 4 :0.25Eu 3+ ,0.005Yb 3+ were utilized as the red-light source. These results indicate that these two phosphors may become reliable red-light sources with high antithermal quenching properties for WLEDs.