Vascular complications induced by diabetes constitute the principal cause of morbidity and mortality in diabetic patients. It has been reported that carvacrol (CAR) possesses a wide range of biological activities. The effects of CAR on diabetes-induced vasculopathy remain unknown. In this study, diabetic mice were created by the intraperitoneal injection of streptozotocin (STZ) in male C57BL/6 J mice to investigate whether CAR provided a protective effect against diabetes-induced vasculopathy and to investigate the underlying mechanisms. We found that CAR decreased blood glucose levels in diabetic mice. Moreover, CAR ameliorated diabetes-induced aortic morphological alterations, as evidenced by an increased thickness in the intima-media width and an increased number of vascular smooth muscle cells (VSMCs) layers. Further studies revealed that CAR inhibited hypercontractility in the aortas of diabetic mice and VSMCs in response to hyperglycemia, as evidenced by the relaxation of phenylephrine(PE)-induced vasoconstriction, the decreased expression of smooth muscle (SM)-α-actin, and the increased expression of Ki67 and proliferating cell nuclear antigen (PCNA). Furthermore, the PI3K/Akt signaling pathway was inhibited in the aortas of diabetic mice and VSMCs in response to hyperglycemia, while CAR treatment activated the PI3K/Akt signaling pathway. In conclusion, our results strongly suggest that CAR plays a protective role in diabetes-induced aortic hypercontractility, possibly by activating the PI3K/Akt signaling pathway. CAR is a potential drug for the treatment of diabetic vasculopathy.