The uniform distribution of nano-sized conductive fillers in conductive papers is still a big challenge. Herein, we report a novel cycled film-liquid interface culture (CFLIC) method to produce flexible, ultra-strong, and highly conductive papers based on bacterial cellulose (BC) and graphene (GE). During this biosynthesis process, the GE nanosheets uniformly dispersed in the culture medium are closely bundled by growing BC nanofibers, which leads to a sophisticated multilayered GE/BC nanocomposite. The as-prepared GE/BC paper shows greatly improved tensile strength (93% improvement) and electrical conductivity (10 orders of improvement) over bare BC paper while still retaining the excellent flexibility of BC paper. The strategy is versatile, facile, and scalable and the resultant paper shows promise in numerous fields such as energy storage and electromagnetic interference shielding.