Abstract The topology and chemical functionality of metal–organic frameworks (MOFs) make them promising candidates for membrane gas separation; however, few meet the criteria for industrial applications, that is, selectivity of >30 for CO 2 /CH 4 and CO 2 /N 2 . This paper reports on a dense CAU‐10‐H MOF membrane that is exceptionally CO 2 ‐selective (ideal selectivity of 42 for CO 2 /N 2 and 95 for CO 2 /CH 4 ). The proposed membrane also achieves the highest CO 2 permeability (approximately 500 Barrer) among existing pure MOF membranes with CO 2 /CH 4 selectivity exceeding 30. State‐of‐the‐art atomistic simulations provide valuable insights into the outstanding separation performance of CAU‐10‐H at the molecular level. Adsorbent–adsorbate Coulombic interactions are identified as a crucial factor in the design of CO 2 ‐selective MOF membranes.