Abstract: Nature provides unique insights into design strategies evolved by living organisms to construct robust materials with a combination of mechanical properties that are challenging to replicate synthetically. Hereby, inspired by the impact-resistant dactyl club of the stomatopod, a mineralized biocomposite is rationally designed and produced in the complex shapes of dental implant crowns exhibiting high strength, stiffness, and fracture toughness. This material consists of an expanded helicoidal organization of cellulose nanocrystals (CNCs) mixed with genetically engineered proteins that regulate both binding to CNCs and in situ growth of reinforcing apatite crystals. Critically, the structural properties emerge from controlled self-assembly across multiple length scales regulated by rational engineering and phase separation of the protein components. This work replicates multiscale biomanufacturing of a model biological material and also offers an innovative platform to synthesize multifunctional biocomposites whose properties can be finely regulated by colloidal self-assembly and engineering of its constitutive protein building blocks.