Borohydrides, known for ultrahigh hydrogen density, are promising hydrogen storage materials but typically require high operating temperatures due to their strong thermodynamic stability. Here we introduce a novel light-induced destabilization mechanism for hydrogen storage reaction of borohydrides under ambient conditions via photogenerated vacancies in LiH. These vacancies thermodynamically destabilize B-H bonds through the spontaneous "strong adsorption" of BH4 groups, which trigger an asymmetric redistribution of electrons, enabling hydrogen release at near room temperature, approximately 300 °C lower than the corresponding thermal process. By utilizing specially designed "nano-photothermal reactors", which optimize thermodynamic destabilization effect with nanoscale dispersed LiH and create space-confined "hotspots" to enhance hydrogen storage kinetics, we achieve an ultrahigh hydrogen storage capacity of 11.02 wt % H2 in LiBH4 using only light irradiation. This light-induced destabilization mechanism can also be extended to other alkali metal borohydrides, offering insights for developing solid-state hydrogen storage materials under mild conditions.