Among the various separation membranes, the thin-film nanocomposites (TFN) membranes have been widely applied for gas separation. In the present study, TFN hollow fiber membranes using polydopamine (PD)-encapsulated ETS-4 (Engelhard titanosilicate-4), PD-ETS-TFN, with a pore size of 3–4 Å were prepared for gas separation applications. The proposed TFN hollow fiber membranes were prepared by condensation-based interfacial polymerization (IP) between poly(ethylenimine) as an aqueous monomer and 1,3,5-benzenetricarbonyl trichloride as an organic monomer on a porous PES poly(ether sulfone) substrate. The dopamine-encapsulated ETS-4 was incorporated inside the polyamide layer to maximize the hydrophilicity of the membrane. Various methods were employed to analyze the structures and characteristics of the ETS-4 and TFN membranes, and tests were conducted to evaluate the permeance of H2, CO2, N2, and CH4 through PD-ETS-TFN. The results revealed a facilitated transport property toward CO2. Due to the molecular sieving effect of the ETS-4, the proposed membranes achieved a permeance as high as 60.4 GPU toward H2 and H2/CO2 selectivity of 14.3. Display omitted •Engelhard titanosilicate-4 was prepared for mixed matrix membranes.•Polyethersulfone hollow fiber membrane was used as a substrate.•Polydopamine-encapsulated ETS-4 thin-film composite hollow fiber membrane was prepared.•Prepared MMMs showed high potential for gas separation.