<p>This research investigated the mechanism by which abscisic acid (ABA) enhances the drought resistance of tomato plants (cv. Rio-Grande) by analyzing the changes in plant physiology, expression of antioxidant ABA-related genes, improving morphological traits and yield. Fully grown (5–6&#xa0;weeks after being transplanted) tomato plants, were subjected to drought stress and ABA treatments in a greenhouse under&#xa0;controlled conditions. Results declared that ABA application maintained plant growth, chlorophyll content, physiology, and yield under drought stress. The application ABA also significantly controlled the glucose and fructose levels in tomato leaves during drought stress. ABA application increased the expression of antioxidant-related genes (<i>SlCAT, SlSOD, SlPOD,</i> and <i>SlAPX</i>), which enhanced plant’s ability to deal with drought stress. Consequently, the ABA treatment also increased the expression level of ABA signaling and biosynthesis genes (<i>SlABF4</i>, <i>SlSnRK2</i>.<i>6, SlNCED1</i>, and <i>SlABI5</i>) under drought stress. The findings indicate that applying ABA may improve the drought stress resilience of tomato plants through the modulation of their physiological, biochemical, and molecular mechanisms.</p> Graphical Abstract <p></p>