Titanium dioxide nanotube (TNT) amalgamated graphene oxide (GO) matrix was blended with cellulose triacetate (CTA) polymer to form a new kind of mixed matrix membranes (MMMs) for the selective biogas upgrading. The effect of hybrid fillers on the physico-chemical, thermal and mechanical properties of membranes were studied using different spectroscopic techniques. Notable improvements on these properties were observed on MMMs as compared to the pristine membrane. Similarly, resulting MMMs exhibited higher CO₂ adsorption affinity. Furthermore, single gas permeation measurements revealed higher permeability as well as selectivity for TNT@GO/CTA membrane. CO₂ permeability increased almost 7 times, reaching 22.54 Barrer, whereas CO₂/CH₄ selectivity increased nearly three folds from 25.06 for the pristine membrane to 86.69 for TNT@GO/CTA membrane and reached the [78] upper bound. The long term stability experiment of the TNT@GO/CTA membrane confirm the anti-aging ability suggesting its practical application in the bio/natural gas upgrading process. These results established an effective modification approach for applying alternative porous hybrid fillers into gas separation applications.