Chitosan, a deacetylated derivative of chitin, has many functional properties that can be used for processing, preservation and as food additive. Chitosan application can be done by edible coatings, direct addition to the batter, and tumbling in the chitosan solution. Chitosan exhibits antioxidant and antimicrobial properties. Here we review applications of chitosan in seafood products and effects on the shelf life of the stored product. Chitosan treatment is effective against two main spoilage factors of seafood: increased oxidation and microbiological spoilage. Chitosan treatment avoids the decrease of sensory scores during storage, and prolongs shelf life of chitosan-treated seafood products.