Glutathione Peroxidase 1 (GPx1) is a crucial cellular antioxidant enzyme that plays a significant role in various biological processes. GPx1 is found in the cytoplasm and mitochondria of mammalian cells and is responsible for the enzymatic reduction of hydrogen peroxide and soluble lipid hydroperoxides using glutathione (GSH) as a source of reducing equivalents. Like most selenoenzymes, GPx1 contains a single redox-sensitive selenocysteine amino acid that is important for its function. Selenium availability and modifiers of selenocysteine incorporation can alter GPx1 expression, which in turn can promote disease states. As an antioxidant enzyme, GPx1 modulates the balance between necessary and harmful levels of ROS. It influences the thiol redox state and maintains the balance between necessary and harmful levels of cellular oxidants. GPx1 has been shown to have protective effects against various neurodegenerative diseases such as Parkinson's, Alzheimer's, brain ischemia, and seizure disorders. It may also play a role in neuropsychiatric conditions like stress, bipolar disorder, schizophrenia, and drug intoxication. GPx1 is involved in the innate immune response to lipopolysaccharide (LPS), protecting the lungs from oxidative damage. It is also implicated in the production of pro-inflammatory cytokines following an LPS attack. Furthermore, GPx1 plays a role in cardiovascular and metabolic health and is considered protective against the development and progression of many chronic diseases.