Reactive astrogliosis, a common phenomenon after central nervous system (CNS) injury, exerts negative effects on neuronal repair and recovery by forming a glial scar. Mitofusin2 (Mfn2), a hyperplasia suppression gene, is a potential target of therapeutics to better control astrogliosis. To simulate traumatic injury of the CNS in vivo, an in vitro scratch injury model was established to investigate the role of Mfn2 in the proliferation of astrocytes in this study. We demonstrated that scratch-injury stimulation upregulated the expression of the markers cyclin D1, PCNA and GFAP and turned quiescent astrocytes into mitotic cells, which may have been via activation of Ras-Raf1-ERK1/2 and PI3K-Akt signaling. Meanwhile, both the gene and protein of Mfn2 were markedly inhibited. Furthermore, overexpression of Mfn2 effectively attenuated astrocyte proliferation and halted the cell cycle, concomitant with marker downregulation and wound healing suppression. Our results demonstrate that overexpression of Mfn2 inhibits the reactive astrogliosis process by blocking the Raf1-ERK1/2 and PI3K-Akt signal pathways. Therapeutic approaches that target Mfn2 may have protective effects against reactive gliosis and glia formation.