Cubic rock salt can lower down or break the rare earth transition barrier through interstitial or vacancy defects owing to its great deformation and rotation flexibility. Here, we demonstrate that oxygen vacancies in SrO are induced by proper oxidization and atmosphere adjustment, resulting in defects with various depths and crystal field distortion. The thermally assisted tunneling from defects to 5D4 state and electronic population decrease on 5D3 state of Tb3+ are observed by the deformation of adjacent oxygen octahedral structure. Finally, the as-prepared SrO: 0.01 ​Tb3+ phosphors, commercial BaMgAl10O17: Eu2+ blue phosphor, and CaAlSiN3: Eu2+ red phosphor are mixed and coated onto 280 ​nm deep-ultraviolet LED chip to assemble white light-emitting LED device. The LEDs show CCT of 3850 ​K, 4136 ​K, and 4741 ​K, with color rendering index of 90.3, 90.8, and 92.1, respectively. These insights will advance the fundamental knowledge of crystal engineering in cubic rock salt, and enable new ways to manipulate energy transfer and electronic transition via defects.