Nanocellulose has attracted a great level of interest in scientific and industry fields as a reinforcing filler in polymeric composite due to its abundant availability, good renewability, good biodegradability, light weight, excellent mechanical properties, and high surface area. The morphology and the preparation methods of nanocellulose are discussed in this chapter. The nanocellulose incorporation polymer composites comprising the processing techniques and the properties of nanocellulose-reinforced biocomposites such as tensile, thermal, barrier, and biodegradation properties are also discussed in this chapter. Understanding of the processing methods and its properties are essential for the researchers to evaluate the suitability of the nanocellulose-reinforced composites for various applications in response to innovative and evolving societal requirements including circular bioeconomy.