The present experiment was designed to determine the efficacy of a commercial source of chitosan (CS) to enhance performance, anti-oxidative function, and immune response in weaned pigs. A total of 60 crossbreed piglets (Duroc × Landrace × Yorkshire), with average live bodyweight of 8.85 ± 1.52 kg, were weaned at 28 ± 2 days and randomly assigned to five treatment groups, which were fed maize-soybean meal diets containing 0 (basal diet, control) and 250, 500, 1000, and 2000 mg/kg CS. The experiment lasted for two weeks. Body weight was recorded and daily feed intake was calculated. Faecal consistency was monitored for the overall period. After two weeks, blood samples were collected and anti-oxidative and immune parameters were determined. The results showed that CS improved average daily gain and daily gain: daily feed intake during the experiment. Mean faecal score values for the second week were improved by CS, which showed decreased values compared with the control diet. The CS increased the total antioxidant capacity and the activities of superoxide dismutase, catalase and glutathione peroxidase and the content of reduced glutathione in serum, and decreased the malondialdehyde and cortisol contents of serum. Furthermore, CS increased the levels of serum IL-1β，IL-2 and IgG. These findings suggested that the use of CS improved performance and anti-oxidative function, and regulated the immune response of weaned pigs.