Thymol oil-in-water nanoemulsions as a potential natural alternative for synthetic antioxidant agents were developed. The nanoemulsions were formulated using Quillaja Saponin bio-surfactant and green solvents including high oleic sunflower oil (HOSO), tricaprylin (TC), and cinnamaldehyde (CA). The 4% thymol nanoemulsions containing TC and HOSO remained stable during long-term storage (at least 30 d). The antioxidant activity (AA) of free thymol and thymol nanoemulsions was compared with butylated hydroxytoluene (BHT) and ascorbic acid. The results obtained from DPPH, FRAP, and CUPRAC antioxidant assays showed a substantial improvement (p < 0.05) of the AA of free thymol through emulsification. The outcomes from the AA of the nanoemulsions in raw chicken breast meat measured by the TBARS assay revealed a significant improvement (p < 0.05) of the AA when thymol was encapsulated. These nanoemulsions may be applicable in the food industry as well as in cosmetic and health care products.