<p>Lithium superionic conductors such as Li_3xLa_2/3−xTiO₃ (LLTO) enable rapid and selective lithium-ion transport through their crystalline frameworks and have been widely explored for lithium extraction. However, their implementation in membrane-based separations is hindered by the need for high-temperature sintering ( &gt; 1000 °C), which leads to high energy consumption and potential lithium volatilization, thereby compromising structural integrity and scalability. Here, we report a structurally integrated composite membrane by embedding LLTO nanoparticles into a ZIF-62 glass matrix via a low-temperature melt-casting strategy, yielding a dense, defect-free membrane with intimate interfacial integration and improved mechanical robustness. Systematic investigations across a wide composition range reveal effective transport channels are highly restricted until a critical content is reached, after which an extensive interconnected LLTO network forms. The optimized membrane exhibits high lithium selectivity and delivers a Li/Mg selectivity of up to ~59,000 in Red Sea water under electrochemical operation, while maintaining stable lithium extraction performance across diverse natural brines. This study establishes a scalable membrane design strategy with good processability, offering broader opportunities for not only lithium extraction, but also ion-selective membranes in electrochemical separations and energy storage systems.</p>