This study investigates the influence of elevated carbon dioxide (CO2) concentrations on tomato plant growth and its subsequent impact on the performance of Spodoptera litura, a common agricultural pest. Tomato plants (Solanum lycopersicum) were exposed to elevated CO2 levels in a controlled environment. Plant growth parameters, such as height, leaf area, and biomass, were monitored. Additionally, the performance of Spodoptera litura larvae feeding on these plants was assessed. The results revealed significant alterations in tomato plant growth under elevated CO2 conditions, including increased biomass. Paradoxically, the performance of Spodoptera litura larvae was impaired when feeding on these plants. This study sheds light on the complex interactions between elevated CO2, plant physiology, and herbivore performance, providing insights into the potential ecological consequences of rising atmospheric CO2 levels.