L-Gulonic acid γ-lactone is primarily used in the synthesis of ascorbic acid (vitamin C), where it serves as a key intermediate in the industrial production process. It plays a crucial role in the Reichstein process, a widely adopted method for manufacturing vitamin C on a large scale. Additionally, it is utilized in biochemical research to study metabolic pathways, particularly those related to carbohydrate metabolism and the biosynthesis of vitamin C in various organisms. Its application extends to the pharmaceutical industry, where it contributes to the development of nutritional supplements and health products aimed at addressing vitamin C deficiencies.