Plant-derived antioxidants have gained increasing attention due to their potential to enhance food preservation while promoting sustainability in packaging solutions. In this context, Camellia japonica leaves emerge as a promising source of natural antioxidant compounds with applications in functional foods and eco-friendly processing technologies. The antioxidant capacity of C. japonica leaf extract was evaluated using DPPH and ABTS radical-scavenging assays, which yielded IC₅₀ values of 33.11 ± 7.25 µg/mL and 23.75 ± 10.97 µg/mL, respectively. Additionally, the total phenolic content (TPC), assessed by the Folin–Ciocalteu assay, was found to be 36.67 ± 4.05 mg GAE/g dry weight, reflecting a high concentration of polyphenolic compounds responsible for the observed bioactivity. These results suggest that C. japonica leaf extract possesses significant potential to inhibit oxidative deterioration, thereby supporting its incorporation into active food packaging systems and as a natural food additive. The integration of such botanical antioxidants in food processing can offer multiple advantages, including extended shelf life, reduced reliance on synthetic preservatives, and improved maintenance of product quality and safety. Nonetheless, before large-scale industrial application, further studies are necessary to assess toxicological safety and possible sensory effects, ensuring consumer acceptance and regulatory compliance. Moreover, investigations into the interactions between the extract, food matrices, and packaging materials will be crucial to determine its practical feasibility. In conclusion, C. japonica leaf extract stands out as a promising natural antioxidant agent that aligns with sustainable food preservation goals, facilitating the development of environmentally friendly packaging and clean-label food products.