Photoluminescence (PL) has been significantly applied in anticounterfeiting and encryption. However, present PL anticounterfeiting and encryption efforts are based on static PL, which is easily counterfeited by substitutes. In this work, a multimode dynamic PL material MgGa 2 O 4 is developed. Under fixed ultraviolet irradiation, the PL color dynamically changes from green to blue in seconds at room temperature and reverses from blue to green in seconds at a higher temperature. It reveals that the dynamic PL is associated with the interactions between intrinsic traps and two PL centers in the material. Inspired by the unique dynamic PL of this material, flexible polydimethylsiloxane-based images are fabricated and applied in PL anticounterfeiting and encryption efforts. Initial work indicates that the PL patterns on images can change dynamically and reversibly at different temperature modes, which is hard to counterfeit. Thus, a new encryption / optical storage technology is designed based on dynamic PL. The encoded information can be easily accessed using an inexpensive portable ultraviolet lamp. The results show that the PL information can be stored in images for a sufficiently long time and that any theft of information will leave a trace. Therefore, the discovery of dynamic PL is a significant advance in PL anticounterfeiting and encryption that can offer more creative designs to safeguard information security.