Jasmonate compounds are known as new plant hormones that play important roles in the regulation of plant growth and development. Mints have been used and valued as aromatic herbs for thousands of years. Peppermint (Mentha piperita L.) is used for medicinal and food purposes and its essential oil is considered industrially important. Peppermint plants were grown in a greenhouse in pots. At flowering phase, the plants were treated with different concentrations of MeJA (0, 0.1, 0.5 mM) and after 24 h were evaluated for their carotenoid, anthocyanin, phenol, flavonol, flavonoid, H2O2, and proline. Analysis of variance indicated that different concentrations of MeJA caused significant variation in all measured traits except proline. As the latest studies indicated that components such as polyphenols, carotenoids, and flavonoids are natural antioxidants, the results of this experiment showed a significant increase in the antioxidant potential of Mentha piperita treated with 0.1 mM MeJA.