||In this work, a high performance self-cross-linked membrane based on the poly(glycidyl methacrylate-g-poly-(propylene glycol))-co-poly(oxyethylene methacrylate) (PGP−POEM) graft copolymer is reported. The self-cross-linking ability of the PGP-POEM graft copolymer originates from the epoxide−amine click chemistry, which takes place under mild conditions without any additional cross-linking agents or catalysts. The self-cross-linking reaction occurred during the membrane drying process without thermal treatment at high temperature. The gas separation properties of the membranes were investigated as a function of POEM content in the copolymer. The PGP-POEM membranes showed the significant enhancement in both permeance and selectivity as the POEM content increased up to 51.2 wt %. The performance of the membrane can be further improved by optimizing the membrane thickness. The best performance of the membrane was close to the target area for commercialization of CO2 capture membranes, showing a CO2 permeance of 500 GPU (1 GPU = 10−6 cm3 (STP)/(s cm2 cmHg)) and CO2/N2 selectivity of 22.4.