<p>Membrane technology is an energy efficient and environment-friendly method for capturing CO₂ from post-combustion flue gas. Carbon capturing efficacy of polymeric membranes restricted by trade-off between gas permeability and selectivity can be overcome by synergistically incorporating bi-fillers in polymer matrix to concoct efficient mixed-matrix membranes. Microporous zeolitic imidazolate frameworks ZIF-67 nanocrystals possessing wide surface area, enhanced thermal stability, and excellent CO₂-affinity along with CNTs were synergistically impregnated in varying concentrations into polyether sulfone matrix to drastically improve carbon capture effectiveness. Morphological, structural, crystalline and thermal characterizations of prepared membranes as measured by SEM, FTIR, XRD and TGA respectively demonstrated improved homogeneous nanofillers dispersion, refined nanofillers-polymer interfacial adhesion, preservation of embedded nanofillers and increased thermal resistance. Moreover, the membrane had a 68.9% increase in mechanical properties as well. Gas permeation measurement performed over synthesized hybrid membranes with optimal loading of ZIF-67 (4 wt%) and CNTs (2 wt%) in polyether sulfone rendered upgraded CO₂ permeability (80 Barrer) and CO₂/N₂ permselectivity (21) in contrast to bare polyether sulfone membrane, both of which fall inside the Robeson upper bound of 2008. Current work provides an efficient way to produce superior mixed-matrix membranes with exceptional CO₂ permselectivity due to synergetic effect of incorporating optimized loading of bi-fillers.</p>