Bioinspired Regenerative Lignification Enables Ultra‐Hard and Sustainable Bamboo Structural Materials

The pursuit of sustainable structural materials requires combining high performance with renewable resources and low environmental impact. Here, we introduce a bioinspired regenerative lignification strategy that reconstructs lignin-like covalent networks directly within bamboo cell walls, condensing a multi-year natural hardening process into hours. Unlike conventional delignification-densification or polymer-filling approaches, this method preserves bamboo's hierarchical architecture while chemically stabilizing its matrix. The resulting ultra-hard bamboo exhibits a tensile strength of 503 MPa and a Brinell hardness of 42.1 HB, with weight-specific values surpassing steels and aluminum alloys. Multi-scale analyses reveal that the synergistic effects of cell-wall densification, enhanced cellulose crystallinity, and resin-cellulose cross-linking drive the performance breakthrough. Beyond strength and hardness, the material demonstrates remarkable flame retardancy, fungal resistance, and dimensional stability in water. Techno-economic and life-cycle assessments confirm competitive costs and substantially lower carbon footprints compared with conventional structural metals and plastics. This scalable, nature-inspired approach establishes a general pathway for transforming abundant biomass into next-generation sustainable materials with performance exceeding traditional engineering alloys.