In summary, we have demonstrated a photosensitized dearomative unsymmetrical diamination of various electron-rich (hetero)arenes that is highly regio-and diastereoselective and runs under mild and transition-metal-and additive-free conditions. The developed bifunctional nitrogen-radical precursors were unprecedented, and were elaborately designed for this transformation to simultaneously generate two N-centered radicals with different reactivities via an energy transfer process. In addition, the protocol was also applicable to a wide range of alkenes. Notably, the formed vicinal diamines bear two differentiated amino functionalities, and either imine or amide units could be easily and orthogonally converted into unprotected amines, thereby facilitating the downstream transformation. We believe that this method represents an operationally simple, effective, and practical route to unsymmetrical vicinal diamines in both academic research and industry.