Chitin and chitosan are natural biopolymers produced mainly from crustacean shells of shrimp, crab and lobsters discarded by sea food-processing industries. Chitosan, the deacetylated form of chitin, it is a copolymer of β-(1–4)-2acetamido-D-glucose and β-(1–4)-2-amino-D-glucose units, due to its unique functional properties and distinctive biological activities, chitosan has received great attention and find wide spectrum of biotechnological applications ranging from the environmental, industrial, to agricultural, and medical fields. In the food sector, these biopolymers are best suited, both in their native and chemically modified forms and offer a distinctive application including water purification, juices clarification and deacidification, food shelf-life extension and preservation from microbial deterioration, food quality improvement, food additive, and biodegradable packaging films formation. This review reports chitosan properties and modifications and explores the role of nanotechnology in creating and developing chitosan nanomaterials adapted for food processing, packaging, storage and safety. Furthermore, summarizes their related applications in the food sector.