Solanum lycopersicum L. is a worldwide grown crop with salient economical values for food industries. A pot experiment was conducted to investigate cadmium toxicity in Solanum lycopersicum L. cv Pusa Ruby and its possible amelioration by foliar supplementation of α-lipoic acid (ALA). Plants were grown under different CdCl₂ concentrations (10, 25, 50, 100 mg kg⁻¹ soil), and were sprayed twice with 0.1 mM ALA at the 30th and 45th day of plant growth. The Cd accumulation, plant growth, toxicity indices, photosynthetic pigments, nitrogen metabolism, and antioxidant enzymes were determined in 60 days old plants. Results showed that Cd accumulation was considerably higher in roots than shoots. Cadmium toxicity decreased the plant growth, photosynthetic pigments, and nitrogen assimilating enzymes activity, while significantly (P ≤ 0.05) enhanced the lipid peroxidation and H₂O₂ accumulation in a dose-dependent manner. Foliar supplementation of ALA alleviated Cd toxicity on photosynthetic pigments and nitrogen metabolism by decreasing the Cd accumulation, toxicity indices, and improving the activity of antioxidant enzymes at each respective Cd treatment. The H₂O₂ and MDA content were decreased by 23% and 55%, respectively, at 10 mg Cd treatment. Under similar conditions, the NR, GOGAT, SOD, and APX activity were enhanced by 10%, 21%, 26%, and 10%, respectively, over the control. The study concludes that ALA can be potentially used in the amelioration of cadmium toxicity in tomato plants.