Metformin, an antidiabetic drug, has been shown to exert neuroprotective, antioxidant and anti-inflammatory properties. Senescent astrocytes have been shown to accumulate with age and in the context of many neurodegenerative diseases. The present study investigated the effects of metformin on the oxidative stress-induced premature senescence in astrocyte cells. For this purpose, primary culture astrocyte cells were pretreated with metformin before the treatment of H 2O 2 every 72 hours. SA-β-galactosidase (SA-β-gal) staining was performed to confirm senescence induction, and followed by mRNA expression analysis of cell cycle inhibitors (p53, p21 WAF1 and p16 INK4a) and senescence-associated secretory phenotype (SASP) proteins by q-PCR. Intracellular reactive oxygen species (ROS) level was measured by DCFH-DA method. H 2O 2 significantly increased the number of SA-β-gal positive cells and mRNA levels of cell cycle repressors (p53 and p21 WAF1) and SASP proteins (IL-6, IL-1β, CXCL1, and CCL2). Metformin pretreatment significantly reduced H 2O 2-induced senescent cell number. H 2O 2–induced increase in levels of p53, p21 WAF1, IL-6, CXCL1, and CCL2 mRNA and ROS was significantly inhibited by metformin. Metformin prevented H 2O 2-induced senescence development by decreasing inflammation and oxidative stress in astrocyte cells and it would be beneficial to support the mechanism of the protective role of metformin on astrocyte senescence in neurodegenerative diseases.