The growing interest in the replacement of synthetic food antioxidants by natural ones has fostered research on the screening of plant-derived raw materials for identifying new antioxidants. The special attention of research today is focused on inexpensive or residual sources from agricultural industries. Fruit peels as sources of powerful natural antioxidants are often the waste parts of various fruits from consumption and food industry. Among the fruit peels, mangosteen peel is an important source of natural phenolic antioxidants. The mangosteen peel contains various bioactive substances, i.e., phenolic acids and flavonoids, which possess biological and medicinal properties, especially antioxidant properties. The aim of this review, after presenting analytical techniques for determining in vitro antioxidant activity of mangosteen peel extract, is to summarize available data on the factors affecting antioxidant activity of mangosteen peel extract. In addition, the potential antioxidant activity of mangosteen peel extract, the bioactive compounds identified from mangosteen peel extract and their antioxidant activity are presented. Potential applications of the mangosteen peel extract in food, pharmaceutical and cosmetic products are also discussed.