Vitamin C or ascorbic acid is used in modern medicine supplements for therapeutic objectives in various disorders associated with oxidative stress, inflammation, and immune dysregulation. In the present review article, updated experimental and clinical studies on anti-inflammatory, antioxidant, and immunomodulatory effects of vitamins C are discussed. Electronic search engines were searched using appropriate keywords until the end of 2022. Vitamin C showed anti-inflammatory effects in various inflammatory disorders through modulating inflammatory cells and mediators. Vitamin C also showed antioxidant effects by reducing or inhibiting the production of reactive oxygen species (ROS), hydroxyl radicals, nitric oxide (NO), superoxide anion, and peroxyl radicals, which leads to alleviating of oxidative stress. The immunomodulatory effect of vitamin C also reported on different immune deficiently associated disorders through immune suppressive or in some cases by immune stimulatory mechanisms. Therefore, reviewed papers indicated potential therapeutic effects of vitamin C on inflammatory, oxidative stress, and/or immune-dysregulation associated disorders.