In this work, we investigated the influence of a novel green flameretardant thermoset complex matrix resin, VEECO, produced by thermoset blending of epoxidized corn oil (ECO) with a vinyl ester (VE) resin. The new polymer blend was made with the ECO content at an optimal amount of 15%. After characterization, it was discovered that the VEECO15 blend cured at 8 h had its glass transition improved by 6.38%. Regarding its mechanical properties, the improvements were as follows: flexural strength, 19.36%; modulus, 123.53%; and impact energy, 29.08%. The flammability property for the heat release rate was improved by 20.62% and, most importantly, emissions of CO and CO 2 were reduced by 62.73 and 49.34%, respectively, demonstrating its potential for sustainability. As a result of the proposed synthesis mechanism, the hydrogen bonding suggests the introduction of ECO as a biobased polymeric material. Overall, the polymer blend offers a new source of hybrid eco-thermoset resin that could mitigate the increasing consumption and environmental impact of BPA-based thermoset polymers. This material is expected to be a potential source of sustainable composites for a rapidly growing carbon-free society and eco-friendly urban development.