AbstractHot electrons activate reactants and reduce the activation energy barrier (Ea) of a reaction through electron donation. However, a comprehensive understanding of the intrinsic driving force of this electron‐donating effect is lacking, let alone the precise manipulation of electron donation processes. Herein, the essential and promotional role of hot electron energy on the electron‐donating effect was elucidated using molecular oxygen activation (MOA) as a model reaction. Through providing an available electron source to the conventional photo‐thermal conversion system, the high energy carried by hot electrons was liberated and greatly enhanced the electron donation towards the LUMO (π*) orbit of O2. The energy was also transferred to O2 and elevated the potential energy surface (PES) of MOA, which was reflected by the enhanced formation of superoxide oxygen anions. As predicted, the Ea of MOA decreased by 45.1 % and exhibited a substantial light dependence, demonstrating that MOA became energy‐efficient due to improved exploitation and conversion of photon energies.