Melatonin, a naturally occurring chemical, has pleiotropic effects across various species. It plays a vital role in animals by regulating the body clock, while in plants, it is known to resist aging. Melatonin is associated with various plant physiological processes, including stress response, plant growth, and flowering time. It has prospects in enhancing and promoting plant growth and development, as well as in strengthening crop yield and increasing sustainability in agriculture. This review summarized the potential roles of melatonin in several plant species, as well as its biosynthetic modes. In addition, we described the recently uncovered melatonin features in plants, summarized the issues and challenges facing plant melatonin research and some feasible solution ideas are proposed.