Ultraviolet (UV) emitting persistent luminescence (PersL) materials have aroused significant interest, owing to their unique self-illuminating high-photo-energy feature under excitation-free conditions. In particular, the advent of X-rays as a charging source for UV PersL has facilitated the control of PersL properties and triggered a breakthrough in possible applications such as X-ray imaging techniques, phototherapy, photocatalysis, and optical information storage. Here, we present novel PersL materials that exhibit ultra-long UV emission for over 2000 h, as detected with a spectrometer. Experimental characterization revealed that the intrinsic oxygen vacancies associated with the local structure of the perovskite LaGaO3 can function as traps, which have super capabilities in energy collection and storage triggered by X-ray irradiation. Notably, this design concept is guided by utilizing an oxygen-defect perovskite as a host, which can serve as powerful guidance for expediting the discovery of new PersL materials. Moreover, due to excellent UV PersL performances, the proposed photodynamic therapy (PDT) platform LaGaO3:Bi,Sb@g-C3N4 demonstrates excellent PDT efficiency in vivo using low-dose X-ray irradiation. Our discovery of this UV PersL material is expected to provide directional solutions and novel perspectives for the development and application of UV luminescence technology.