Mango ginger (MG) exhibits antioxidant, anti‐inflammatory, and antihyperglycemic effects; however, the exact mechanism of action of MG extract in relation to its antidiabetic properties remains unclear. To investigate the potential antidiabetic effect of MG extract, we used a high‐fat diet (HFD)/low‐dose streptozotocin (STZ)‐induced type 2 diabetic rat model. A total of 28 male Wistar rats were randomly divided into four groups: (i) Control, (ii) MG (50 mg/kg/day of MG extract), (iii) HFD + STZ (40 mg/kg i.p.), and (iv) HFD + STZ + MG. Following a 12‐week administration of MG extract, significant reductions were observed in serum glucose, insulin, free fatty acid, cholesterol, and triglyceride levels in diabetic rats (p < .0001 for all). MG extract supplementation led to an increase in the total antioxidant capacity of the serum and a decrease in malondialdehyde (MDA) levels in both the serum and liver (p < .0001). Furthermore, hepatocellular fat accumulation was partially attenuated in the HFD + STZ + MG group. Notably, MG extract inhibited glycogen synthase kinase‐3β (GSK‐3β) in the liver (p < .01) and downregulated Fyn expression, resulting in elevated nuclear factor erythroid 2–related factor 2 (Nrf2) activity in the HFD + STZ + MG group compared to the HFD + STZ group (p < .05). The increased activity of Nrf2 in the HFD + STZ + MG group likely promoted the upregulation of heme oxygenase 1 (HO‐1) in the liver (p < .0001). In conclusion, MG extract may exert antidiabetic effects by augmenting the antioxidant defense system through the regulation of GSK‐3β/Fyn/Nrf2 in a rat model of type 2 diabetes.