Entropy‐driven strategy enables the systematic design of complex systems by using entropy as a quantifiable design parameter for the degree of mixing. In this study, we present mixed‐linker zeolitic imidazolate frameworks (ZIFs), sod‐ZIF‐1 series, that features two types of six‐membered rings (6MRs) with aperture sizes of 3.4 Å and 1.7 Å. By adjusting the configurational entropy, the ratio of these 6MRs can be systematically controlled, which significantly influences adsorptive properties, particularly improving the H2 affinity about 3 times throughout the series. This results in the significant enhancement of retention times in dynamic separation of hydrogen isotopes (D2/H2), even over LNG liquefaction temperature. This approach to entropy‐driven pore engineering provides new opportunities for enhancing gas adsorption and separation processes.