Immobilizing amino acid ionic liquids (AAILs) into a porous support is a promising way to fabricate robust solid sorbents with high capacities for CO2 capture. One of important factors to be evaluated toward the practical use is the impact of water vapor in inlet gases on the CO2 capture performance as real flue gases contain some fraction of water vapor. In this study, CO2 sorption-desorption experiments of supported 1-ethyl-3-methylimidazolium amino acid ([EMIM][AA]) IL sorbents on porous microspheres were conducted under dry and humidified CO2 inlet conditions using a TGA-MS analysis system, and their outcomes were compared with those of supported amino acids (AA) sorbents. The presence of water vapor changed the CO2 sorption behaviors depending on the sorbent types. In humidified CO2 inlet, the CO2 capture capacities of supported [EMIM][glycine] and [EMIM][lysine] decreased as the adsorbed water hindered their reaction with CO2, whereas the CO2 capture of those with supported lysine and arginine increased, since water content exerted a positive impact on the CO2 capture behavior.