The thermal quenching effect of phosphors restricts the practical application due to the serious energy loss. Herein, excellent thermal stability of Eu3+ emission is observed in the α-Ba2ScAlO5:xEu3+ phosphors. The compounds crystallize in the hexagonal sole-phase structure with partial replacement of Sc3+ by Eu3+. Apart from the 4f6→4f6 transitions, luminescence excitation spectra of α-Ba2ScAlO5: xEu3+ show an intense charge transfer band (CTB). Upon excitation into the CTB, the emission of Eu3+ shows normal thermal quenching with intensity at 210 °C keeping 70% of that measured at room temperature. When excited into the characteristic line at 393 nm, the emission of Eu3+ demonstrates even better thermal stability while photoluminescence intensity declines by only 5% at 210 °C compared to that at room temperature. The CTB is shown to play a role of an intermediate level to impact the energy transfer mechanism responsible for excellent thermal stability.