Mechanoluminescent materials have broad application prospects in advanced displays, stress imaging, and anti‐counterfeiting owing to their ability to convert mechanical stimuli into light. However, most previous studies have focused on the visible and near‐infrared regions. Although natural ultraviolet C (UVC) light is nearly absent on the Earth's surface, it plays an important role in many fields. Therefore, the development of smart materials capable of emitting UVC mechanoluminescence (ML) and expanding the application scenarios of UVC ML are significant but challenging. Here the ML property of Sr ₂P ₂O ₇:Pr ³⁺ is examined, which stems from the 5d→4f transition of Pr ³⁺ and is located over the UVC region. The peak wavelength of the UVC ML of Sr ₂P ₂O ₇:Pr ³⁺ is ≈230 nm, which is, to the best of this knowledge, the shortest ML wavelength reported to date. It is further demonstrated that the UVC ML of Sr ₂P ₂O …