Chitosan is a biocompatible, biodegradable, nontoxic, and cationic carbohydrate derived from one of the most abundant polymer in nature: chitin. The cationic character also gives chitosan antibacterial and antimicrobial properties as well as special features such as solubility in acidic media and capability for establishing electronic interactions with anionic groups, through their NH3+ groups that are positively charged in acidic media. Due to these inherent properties, added to its reactivity and ability to form gels, films, and nanoparticles, chitosan is used in a wide variety of applications, which include drug delivery, wound healing, tissue engineering, membrane separation, and water treatment, as biopesticide and food packaging. Chitosan coatings and films for food packaging act as physical barriers, reduce gas exchange, and can inhibit spoilage and the growth of pathogenic microorganisms, thereby prolonging the shelf life of food. They are also an environmentally friendly option compared to petroleum-derived plastic packaging, which is generally not biodegradable. Chitosan can be chemically modified, blended with biological and synthetic polymers, reinforced using micro- and nanofillers, and loaded with active compounds to further enhance its useful attributes and minimize its drawbacks. These modification strategies, used alone or in combination, enabled the fabrication of efficient smart food packaging based on chitosan, which has amply demonstrated its ability to significantly improve food safety and quality while remaining aligned with sustainable growth goals. Therefore, this chapter presents a detailed discussion of the latest developments in the use of this outstanding biopolymer for smart and sustainable packaging applications.