This study demonstrated that disease resistance against anthracnose (caused by Colletotrichum camelliae) in camellia (Camellia pitardii) could be induced by chitosan oligosaccharide (COS) applied to leaves at 50 µg/ml. The induced resistance lasted for 10–15 days, with the optimum induced effect against anthracnose occurring by the third day. Following treatment with C. camelliae alone, COS alone and C. camelliae and COS combined, camellia plants showed different responses, which included the activity of H2O2, the defence-related enzymes, such as polyphenol oxidase, peroxidase, catalase, phenylalanine ammonialyase, and concentration of soluble proteins. Plants that received COS treatments consistently had higher levels of biochemical activity than plants not treated with COS. Assessment of anthracnose severity on infected plants, as evidenced by reduced lesions on leaves, indicated that COS-induced camellia plants had significantly lower disease ratings. To our knowledge, we are first to report the inducement by COS on camellia against anthracnose.