This study advances the synthesis of MOF-COF hybrids by shifting from conventional physical blending to chemically integrated single crystals. COFs are used as active structural units—a conceptual leap enabling rational design of composite frameworks. Yet critical challenges remain: general applicability across material systems, scalability for production, and long-term structural and functional stability. Still, the combination of tunable porosity and cooperative functionality makes COF-MOF composites a promising platform for gas separation/storage, catalysis, and molecular sensing.