Physicochemical, binding, antioxidant and antibacterial properties of chitosans prepared from ground and entire crab leg shells were compared. Chitosan prepared from ground shell (designated as g-chitosan) had significantly higher nitrogen content, degree of deacetylation, solubility and viscosity, but lower ash content, bulk density and colour redness (a*) value than chitosan prepared from entire shell (designated as e-chitosan). Compared with e-chitosan, g-chitosan had comparable water-binding capacity, but higher fat-binding and dye-binding capacity, DPPH radical scavenging activity and antibacterial activity against two Gram-negative (Salmonella Enteritidis and Escherichia coli) and two Gram-positive (Listeria monocytogenes and Staphylococcus aureus) bacteria. This study demonstrated that chitosans prepared from ground and entire crab leg shell exhibited drastic differences in their physicochemical and functional characteristics. These differences were contributed by the particle size of the crab shell.