<p>The present study aimed to investigate the efficacy of exogenously applied ascorbic acid in mitigating the detrimental effects of Cd stress on tomato seedlings. Tomato seeds were exposed simultaneously to Cd stress and foliar spray of ascorbic acid (AsA). Sampling was performed 15 days after treatment. Our findings revealed Cd accumulation led to retardation in growth parameters, nutrient deficiencies, reduced photosynthetic efficiency, impaired redox state, and oxidative damage to cellular membranes. Expression of photosynthetic genes, <i>psaA</i>, <i>psaB</i>, <i>psaC</i>, and <i>psaD</i> decreased by 48%, 62%, 75%, and 69% respectively, under Cd stress. However, exogenous AsA-treated plants exhibited promoted growth, improved nutrient and photosynthetic pigment content, and a higher AsA/DHA ratio. The adverse effects of Cd toxicity on the photosynthetic parameters and expression of photosynthetic genes (<i>psaA</i>, <i>psaB</i>, <i>psaC</i>, and <i>psaD</i>) were significantly attenuated by AsA. Application of AsA restored the activities of ascorbate peroxidase, monodehydroascorbate reductase, and dehydroascorbate reductase. AsA treatment reduced the concentration of H₂O₂ and MDA, and the electrolyte leakage rate in Cd-stressed plants by 32%, 47%, and 10%, respectively. This study demonstrates the significant potential of exogenously applied AsA in mitigating the adverse effects of Cd toxicity in tomato plants. The use of AsA could be considered as a promising strategy to enhance crop resilience and productivity in Cd-contaminated environments, offering a practical solution for sustainable agriculture in areas affected by heavy metal pollution.</p>