BC is an incredibly robust material, with an estimated modulus of over 100 GPa and a strength exceeding 1.5 GPa. It is truly one of nature's strongest creations. Research has shown the effectiveness of using BC as a nano-additive in polymeric materials leading to the formation of lightweight and superior strength nanocomposites at high fiber fractions of BC in the matrices. This chapter explores the various uses of BC in polymers and rubber nanocomposites. These materials consist of nanocomposites that are transparent to light and composites that have been reinforced with BC and natural fibres, creating a hierarchical structure. It covers the synthesis, properties, and applications of these advanced materials. Emphasis is placed on the synergy between BC and rubber matrices, the techniques employed for their fabrication, and their enhanced mechanical, thermal, and biocompatible properties. The potential applications of BC/rubber composites in various industries, including biomedical, automotive, and electronics, are discussed. The authors have explored the application of BC in various cellulosic and biomimetic composites. This chapter also highlights then the usage of BC in the production of BC/rubber nanocomposites.