Metformin is one of the oldest and commonly used blood sugar lowering drugs, having limited side effects and used as the first line treatment in patients suffering from diabetes mellitus. Moreover, various studies have emphasized on the anti-inflammatory and antioxidant role of metformin, with multiple mechanisms, which activation of AMPK by metformin has had a key role in many of them. During the searches on the internet websites of PubMed, Elsevier, Google Scholar, and Science Direct, 76 papers related to the anti-inflammatory and antioxidant role of metformin were selected and reviewed since 2003 to 2017. At the cellular level, metformin suppresses the inflammation in many cases and reduces or eliminates inflammatory factors mainly through dependent mechanisms and sometimes independent of AMPK at the cellular level and through other ways at the systematic levels. It is also effective in reducing the level of oxidative stress factors by regulating the antioxidant system of the cell. All evidence suggests the antioxidant and anti-inflammatory role of metformin in various conditions. Metformin can be an appropriate treatment option for many diseases, which inflammatory processes and oxidative stress play a role in their pathogenesis.