Although a variety ofnanoparticles with better-than-bulk material performances can be synthesized,it remains a challenge to scale the extraordinary properties of individual nanoscale units to the macroscopic level for bulk nanostructured materials.Here,we report a general and scalable biosynthesis strategy that involves simultaneous growth of cellulose nanofibrils through microbial fermentation and co-deposition of various kinds ofnanoscale building blocks (NBBs) through aerosol feeding on solid culture substrates.We employ this biosynthesis strategy to assemble a wide range of NBBs into cellulose nanofibril-based bulk nanocomposites.In particular,the biosynthesized carbon nanotubes/bacterial cellulose nanocomposites that consist of integrated 3D cellulose nanofibril networks simultaneously achieve an extremely high mechanical strength and electrical conductivity,and thus exhibit outstanding performance as high-strength lightweight electromagnetic interference shielding materials.The biosynthesis approach represents a general and efficient strategy for large-scale production of functional bulk nanocomposites with enhanced performances for practical applications.Industrial-scale production of these bulk nanocomposite materials for practical applications can be expected in the near future.