The selective capture of carbon dioxide in the presence of water is an outstanding challenge. Here, we show that the interior of IRMOF-74-III can be covalently functionalized with primary amine (IRMOF-74-III-CH2NH2) and used for the selective capture of CO2 in 65% relative humidity. This study encompasses the synthesis, structural characterization, gas adsorption, and CO2 capture properties of variously functionalized IRMOF-74-III compounds (IRMOF-74-III-CH3, -NH2, -CH2NHBoc, -CH2NMeBoc, -CH2NH2, and -CH2NHMe). Cross-polarization magic angle spinning (13)C NMR spectra showed that CO2 binds chemically to IRMOF-74-III-CH2NH2 and -CH2NHMe to make carbamic species. Carbon dioxide isotherms and breakthrough experiments show that IRMOF-74-III-CH2NH2 is especially efficient at taking up CO2 (3.2 mmol of CO2 per gram at 800 Torr) and, more significantly, removing CO2 from wet nitrogen gas streams with breakthrough time of 610 ± 10 s g(-1) and full preservation of the IRMOF structure.