<p>The fixation and conversion of CO₂ from medium- and high-temperature industrial exhaust gases are scientifically important and challenging tasks owing to the harsh conditions required. Ga₂O₃, a stable <i>p</i>-block compound, is surprisingly active in the thermal conversion of hot CO₂ waste gas, but its underlying mechanism remains unclear. In this study, we investigated CO₂ adsorption and activation across 11 different Ga₂O₃-terminated faces using density functional theory. Charge transfer and chemical bond analyses revealed the occurrence of two distinct activation mechanisms involving synchronous electron gain and loss, driven by a strong synergetic effect between Ga cations and O anions on the substrate surface. This Ga-O synergy enhances the CO₂ activation efficiency compared with single active sites, with CO₂^δ+ cation more readily capturing H atom than CO₂^δ−. To the best of our knowledge, such a dual activation mechanism has not been reported before, particularly for <i>p</i>-block catalysts. Our findings provide new insights into the direct catalytic conversion of CO₂ emissions and offer strategies for the rational design of industrial-grade catalysts for medium- and high-temperature CO₂ tail gas conversion.</p>