High-current reliability remains a key factor hindering the commercialization of AlGaN-based deep-ultraviolet LEDs, primarily due to elusive defect-mediated degradation. Here, we investigate the spatial distribution and nature of defects induced by high current stress in 276 nm AlGaN-based LEDs grown on high-quality AlN. The results demonstrate that the stress-induced defects are generated within the p-type layer and the active region, particularly in areas of current crowding. A combined analysis using capacitance–voltage measurements, deep-level transient spectroscopy, and admittance spectroscopy reveals that p-layer degradation is driven by nitrogen vacancy (V_N)-related defects originating from the dehydrogenation of hydrogen-passivated complexes. In the active region, the dominant stress-induced defects are identified as magnesium substituting gallium (Mg_Ga), V_N, gallium vacancy (V_Ga) complexes, and gallium-nitrogen vacancy (V_Ga-V_N) complexes. These defects act as non-radiative recombination centers, enhancing non-radiative recombination and leading to a reduction in optical power. These findings suggest that mitigating hydrogen incorporation and optimizing current spreading are critical to high-current reliability of AlGaN-based deep-ultraviolet LEDs.