Increasing energy cost, heavy legislative pressures, consumer's demand for environmental friendlier products, carbon neutral technologies and a sustainable future have all triggered fresh interest in research and development of green(er) materials. In this context, cellulose nanofibres are regarded as the prime candidate for the production of high performance sustainable composites. However, the high tensile stiffness (up to 160 GPa) and strength (at least 1 GPa) of a single cellulose nanofibre has yet to be fully exploited in composite materials. Numerous researchers have already manufactured bacterial cellulose (BC)- or nanofibrillated cellulose (NFC)-reinforced polymer composites. Whilst these studies showed the ability of nanocellulose to improve the mechanical performance of polymer matrices, many of these nanocomposites still performed worse than or only equally well compared to PLA, which is one of the highest performing bio-derived polymers that is commercially available at a reasonable price. This proposed project aims to develop the next generation of nanocellulose-reinforced polymers applying green engineering principles to reduce the use of solvents and energy, as well as introduce simple manufacturing concepts to produce sustainable nanocomposites that are truly high performance for high volume structural applications. To achieve this, this project will concentrate on the use of: (i) ultra-low grammage or (ii) high performance cellulose "nanopapers" as the building blocks for sustainable composite materials. It can be anticipated that such truly green and high performance nanofibre composites will find wider applications for instance in the composite, plastic electronics and flexible display industries.