The present invention provides a fusion protein comprising an FGF21 mutant protein and an Fc region of an immunoglobulin. The fusion protein according to the present invention exhibits improved pharmacological efficacy, in vivo duration and protein stability, and a pharmaceutical composition comprising the fusion protein as an active ingredient may be effectively used as a therapeutic agent for diabetes, obesity, dyslipidemia, metabolic syndrome, non-alcoholic fatty liver disease or non-alcoholic steatohepatitis.