The protein–vanadium complex was successfully synthesized and systematically characterized using electron paramagnetic resonance, Fourier transform‐infrared spectroscopy and thermogravimetric analysis. The antioxidant activity analysis indicated that it had better radical scavenging activity on 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH), 2,2′‐azinobis (3‐ethylbenzothiazoline)‐6‐sulfonic acid (ABTS) and O2− compared with the free protein and vanadate. Additionally, the complex exhibited high anti‐diabetic activity against Saccharomyces cerevisiae α‐glucosidase and rat intestinal maltase with IC50 values of 258.53 and 72.41 μg/ml, respectively. Kinetics study showed that the complex was a mixed inhibition type against S. cerevisiae α‐glucosidase and uncompetitive inhibition type against rat intestinal maltase. These indicated that the complex with antioxidant and anti‐diabetic potential could be used for lowering blood glucose that might be caused by insufficient secretion of insulin in the body or excess fat storage. Our findings provide a new protein–vanadium complex for further use in diabetes mellitus or obesity.