Sodium alginate and cellulose were combined to use as a composite carrier for Pseudomonas sp. CUY8 chitosanase immobilization. For free enzyme, immobilized chitosanase within different carriers of sodium alginate and composite carrier, Km values were 1.919, 9.27, and 5.91µM, respectively. The increase of Km value of immobilized chitosanase with composite carrier was lower than that of single carrier. This indicates that the composite carrier of sodium alginate/ cellulose improves the affinity of chitosanase to the substrate. Furthermore, chitosanase immobilization using composite carrier shows improved thermal stability ranging from 65 to 80°C, and enzyme residual activities were more than 75%. The effects of ratio of enzyme to substrate on chitooligosaccharides (COS) production were determined, and COS yields with composite carrier was 68% at optimum ratio of 1:1. Since the immobilization process using composite carrier is simple and effective, this method could be used for the industrial production of COS.