Near‐infrared (NIR) light is promising for bioimaging and information technology due to its high penetration ability and resistance to interference with environmental radiation. Here, a new class of lanthanide‐doped SrZnOSe crystals are developed for the self‐sustainable generation of NIR emissions under mechanical excitation. It is shown that the SrZnOSe crystals render ≈5‐fold stronger NIR emissions than the well‐established CaZnOS due to the low phonon energies of the selenide host, as confirmed by Raman spectroscopy. The potential utility of the crystals is demonstrated by integration with a mouthguard, which can generate bright NIR emissions by bite force to transmit encrypted optical signals through thick tissues (up to 8 mm) in ambient environments. The findings provide a powerful addition to the toolbox of self‐recovery mechanoluminescent materials and open new possibilities for applied research.