Metal-organic framework (MOF) membranes have garnered notable interest in molecular separation. However, their high-pressure application is severely hampered by the mechanical fragility stemming from weak interactions at grain boundaries. Inspired by the cuttlebone’s wall-cavity structure, we develop a class of nanosheets-bridged MOF membranes (NB-MOFs). These graphene oxide nanosheets act as a rigid wall, bridging soft MOF grains and dispersing accumulated stresses at grain boundaries under external loadings, thereby preventing structural cracking and enhancing the mechanical robustness of crystal membranes. By fine-tuning the morphology and content of nanosheets, the optimized NB–ZIF-8 membranes are endowed with unprecedented 50-bar pressure resistance and superior C 3 H 6 /C 3 H 8 separation performance, with a separation factor >240 maintained above 300 hours at industry-relevant pressure. We also confirm our strategy’s versatility by fabricating pressure-resistant NB–ZIF-67 membrane and commercial polymer-supported NB-MOF membranes. We envision that our strategy will establish a platform for developing durable crystalline membranes and unlock their potential in real-world scenarios.