Heat stress is an environmental problem that can negatively impact tomato productivity by reducing fruit setting and disrupting pollen development. The present study aims to understand the molecular mechanism of heat tolerance induced by L-ascorbic acid. Plants were grown in the summer of 2022 (day and night temperatures were 34.4°C and 25.2°C respectively). The plants were divided into two groups: one was sprayed with L-ascorbic acid (0.5 mM) and the other served as a control. Growth parameters, antioxidant enzymes, proline, hydrogen peroxide, and malondialdehyde levels in the leaves were determined. Additionally, a molecular docking allowed understanding the interaction between the antioxidant enzymes and L-ascorbic acid. Results indicated that L-ascorbic acid increased antioxidant enzyme activities (catalase, peroxidase, ascorbate peroxidase, polyphenol oxidase), proline content, fruit setting and growth indicators (shoot and root fresh and dry weight). It also reduced hydrogen peroxide and malondialdehyde levels in tomato leaves. Furthermore, the in-silico analysis revealed that L-ascorbic acid binding energies toward antioxidant enzymes were similar to those of known activators. In conclusion, foliar application of L-ascorbic acid (0.5 mM) effectively mitigated heat stress effects, activating antioxidant enzymes and eliminating reactive oxygen species, ultimately resulting in increased fruit setting.