Stimuli-responsive Pickering emulsions have aroused considerable amounts of attention recently because of their potential for on-demand demulsification. Metal–organic frameworks (MOFs) are promising emulsifiers for the construction of Pickering emulsions due to their ultrahigh specific surface area, tunable porosity, and designable structures. However, CO2-responsive zirconium-based MOF-stabilized Pickering emulsions have been rarely reported up to now. Herein, a new series of amine-functionalized UiO-66-O-APTES were developed via the covalent post-modification of UiO-66-OH with different amounts of (3-aminopropyl)triethoxysilane (APTES) and were then applied to construct CO2-switchable Pickering emulsions. It was shown that UiO-66-O-APTES could emulsify toluene and water well to form an emulsion even at the content of 0.1 wt %. Significantly, the Pickering emulsion could be reversibly demulsified and re-emulsified by alternate CO2 and N2 bubbling under constant pressure. Mechanism results revealed that the CO2-switchable phase transition based on the formation of hydrophilic ammonium salts resulting from the reaction of APTES with CO2, which lowered the wettability of particles, reduced emulsion stability, and resulted in emulsion breaking. After CO2 was removed, the Pickering emulsion could be rebuilt by the reverse reaction. By using this strategy, a controllable and highly effective CuI-catalyzed cycloaddition reaction has been achieved, and the coupling of efficient condensation, product separation, and recovery of MOF catalysts has been demonstrated to give rise to a sustainable reaction process.