Recently, a few-layered graphene oxide (GO) has been extensively investigated as a membrane material for gas and liquid separation. Although GO membrane is considered as one of promising membranes, it has a limitation to apply for practical application because of low gas permeability and low stability under dry condition. In general, small molecules such as gas, water, and ion are passed along the layered structure, which lead to increase of diffusion path. As such, in this study, we prepared porous GO sheets by generating and decorating the holes on the basal plane of GO sheets using simple modification method without any chemical or thermal reduction, as a result, maintaining original GO functional groups such as epoxy, hydroxyl and carboxyl groups. After stacking the porous GO sheets, we have found that empty holes could be formed between stacked GO layers. The empty holes (or pores) can be a route to reduce diffusion penalty for small molecules and then, it can lead to an increase of mass transport rate than that of pristine GO membranes with high aspect ratio. Especially, GO membrane derived from individual porous GO sheets have a ‘nanopocket’, which can contain large amount of water or CO2, surrounded by amine functionalized edges around nanopockets. From these reasons, the CO2 permeability was significantly increased by approximately 30 times compared to the pristine GO membrane and CO2/N2 selectivity was increased up to as high as 30. These results have the potential to open up new approaches for an improvement in the transport and absorption properties of porous two-dimensional membrane material for use in next-generation CO2-selective membranes.