We prepared dense flat-sheet Ag-functionalized carbon molecular-sieve (CMS) membranes from blends of P84 co-polyimide and a sulfonated poly(ether ether ketone) with a Ag+ counterion (AgSPEEK). These blends offer the possibility of producing new functionalized precursor structures, which were previously not possible, such as integrally skinned asymmetric hollow fibers. Membranes prepared at a pyrolysis end temperature of 800 °C showed a maximum permeability for all tested gases at a Ag content of approximately 2.5 wt.-% (He permeability PHe = 465 Barrer (1 Barrer = 7.5 × 10-18 m2 s-1 Pa-1), PCO2 = 366 Barrer, PO2 = 91.8 Barrer, PN2 = 10.3 Barrer). The maximum achieved selectivity for O2 over N2 with CMS membranes based on these blends was O2/N2 = 13.5 (Ag content: 4.5 wt.-%, PO2 = 52.7 Barrer). The CO2 over N2 selectivity reached a value of 48.9 (Ag content: 4.5 wt.-%, PCO2 = 191 Barrer). These observations are explained by the formation of selective bypasses around Ag nanoclusters in the CMS matrix.