The intensity of the recent rise in air temperature brought on by global warming is a significant issue that requires attention. Temperature is the most significant abiotic stressor that plants are subjected and numerous plant growth and development processes, including cellular membrane organization, food and water uptake, germination, antioxidant function, viability, photosynthesis, leaf senescence, starch accumulation, biomass output, and root growth, are impacted by temperature stress. The productivity could be significantly increased by comprehending the molecular and physiological mechanisms underlying abiotic stress tolerance. The use of biostimulants can significantly boost plant resistance to abiotic stresses without endangering the ecosystem. A multipurpose benefit like melatonin (MT) protects the plants against the damaging effects of heat stress (HS). By preserving the water content, protecting the membranes, and enhancing homeostasis (nutrients) and water efficiency (WUE), MT enhances plant growth and development during the HS. Moreover, by activating the antioxidant defense system, MT enhances gene expression, hormone and osmolyte interaction, and decreases the buildup of reactive oxygen species (ROS), all of which contribute to improved resistance to HS. To provide HS tolerance, high endogenous MT boosts antioxidant activity and gene expression. Therefore, understanding the specific roles of both exogenous and endogenous melatonin (MT) is essential for developing HS tolerance in plants. This chapter highlights the potential of MT in enhancing plant responses to HS. It also explores MT’s antioxidant properties, its interactions with other plant hormones, and successful genetic engineering approaches that have improved plant resilience to heat stress.