Rosamultin (Rosa), a natural small-molecule compound, is known for its protective activity against hypoxia-induced injury, but its role in cerebral ischemic stroke injury remains unclear. To assess Rosa's effects on cerebral ischemic stroke, the intraluminal filament method was used to construct the middle cerebral artery occlusion and reperfusion (MCAO) in vivo model with 1 h occlusion and 48 h reperfusion. In addition, an oxygen-glucose deprivation and reoxygenation (OGD/R) in vitro model was constructed using HT22 cells. The protective role and underlying mechanism of Rosa on cell injury was also determined in vivo and in vitro. Rosa notably inhibited neurological deficits and diminished infarct volume and neuronal apoptosis in mice exposed to MCAO. Rosa also exerted neuroprotection in the OGD/R model by improving cell viability, decreasing apoptosis, and enhancing the p-Akt and p-mTOR levels. However, LY294002, a PI3K inhibitor, restored the beneficial influences of Rosa after OGD/R. Moreover, Rosa treatment inhibited autophagy levels, and LY294002 partially restored the inhibition of autophagy levels caused by Rosa in the OGD/R model. In addition, Rosa enhanced the p-Akt and p-mTOR levels and inhibited autophagy levels in mice after MCAO. Rosa could attenuate autophagy via activating the PI3K/Akt/mTOR axis, thereby alleviating cerebral ischemia stroke injury.