A first-principles calculation was performed to investigate the switchable CO₂ capture on χ₃-borophene by injecting/removing the extra electrons. The results show that the CO₂ adsorption energy on the neutral χ₃-borophene is 0.150 eV. After extra 2.5 e are injected, the adsorption energy is raised up to 0.802 eV, showing a significant enhancement with the change from the physical adsorption to chemical adsorption. Furthermore, both the CO₂ capture and release processes are exothermic reactions involving injecting/removing extra electrons. χ₃-borophene possesses a metallic electronic structure, which is conducive to the injection of extra electrons. The minimum charge density for CO₂ capture on the negatively charged χ₃-borophene is 1.6 × 10¹⁴ e cm⁻². The CO₂ capture capacity of χ₃-borophene is 4.09 × 10¹⁴ cm⁻². Finally, we study the selectivity of negatively charged χ₃-borophene. The results show that the negatively-charged χ₃-borophene possesses a high selectivity for CO₂ from its mixtures with CO, CH₄, NH₃, N₂, H₂S, and H₂. χ₃-borophene is a new promising charge-modulated switchable CO₂ capture material with good stability, high CO₂ capture capacity, high selectivity, and excellent electrical conductivity.