This review provides a comprehensive overview of recent advancements in cellulose-based functional materials, focusing on their classification, properties, and applications. Cellulose, due to its abundant natural sources and excellent biocompatibility, has garnered significant interest in the development of biodegradable materials. The review categorizes cellulose based on its morphologies (such as nanocrystals, nanospheres, and hollow ring cellulose) and derivatives (such as methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and cellulose acetate). It discusses the enhanced mechanical properties, antibacterial characteristics, gas regulation, and hydrophobicity of cellulose-based films, along with the underlying mechanisms. The applications of these materials in food packaging, medical supplies, and electronic devices are highlighted, and the challenges and future prospects for their development are outlined. The review also emphasizes the potential of cellulose nanocrystals (CNCs) as fillers in composites, noting their excellent physical, chemical, and ecological properties, and their ability to enhance the mechanical properties and biodegradability of composite materials.This review provides a comprehensive overview of recent advancements in cellulose-based functional materials, focusing on their classification, properties, and applications. Cellulose, due to its abundant natural sources and excellent biocompatibility, has garnered significant interest in the development of biodegradable materials. The review categorizes cellulose based on its morphologies (such as nanocrystals, nanospheres, and hollow ring cellulose) and derivatives (such as methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and cellulose acetate). It discusses the enhanced mechanical properties, antibacterial characteristics, gas regulation, and hydrophobicity of cellulose-based films, along with the underlying mechanisms. The applications of these materials in food packaging, medical supplies, and electronic devices are highlighted, and the challenges and future prospects for their development are outlined. The review also emphasizes the potential of cellulose nanocrystals (CNCs) as fillers in composites, noting their excellent physical, chemical, and ecological properties, and their ability to enhance the mechanical properties and biodegradability of composite materials.