Cellulose is an abundant, naturally occurring and bio-degradable material that has been examined as a possible replacement for conventional materials such as plastics which are known to be toxic to the environment. Cellulose nanomaterials, which can be produced directly from cellulose, offer unique properties and structures that have proven useful for a myriad of applications globally. Currently, cellulose nanomaterials have found widespread use in numerous fields including the biomedical, pharmaceutical, packaging, and the food technology industries. Thus, this chapter reports on the properties of cellulose nanomaterials and cellulose nanocomposites and their use in various fields or industries.