Conventional separation technologies to separate valuable commodities are energy intensive, consuming 15% of worldwide energy. Mixed-matrix membranes, combining processable polymers and selective adsorbents, offer the potential to deploy adsorbent distinct separation properties into processable matrix. We reported a concept for the construction of a mixed-matrix MOF (MMMOF) membrane based on three interlocked criteria: (i) a MOF filler with optimal pore size and shape, functionality, and a host-guest interaction that selectively enhances H2S and CO2 diffusion while excluding CH4; (ii) tailoring MOF crystal morphology along 001 crystallographic direction into high-aspect-ratio (001) nanosheets that proffer maximum exposure of 1D channel and promote nanosheet-polymer interaction resulting in high nanosheet loading; and (iii) in-plane alignment of (001) nanosheets in a polymer matrix with proximal distance to translate the molecular separation properties of single nanosheets into a uniformly [001]-oriented macroscopic MMMOF membrane. This approach offers great potential to translate other key adsorbents into processable matrix.