Fresh chicken meat is a very perishable good, even at refrigerated storage conditions, due to psychrophilic microbial growth and physicochemical changes. The present study focuses on the use of rosemary (Rosmarinus officinalisL.) essential oil (REO), supercritical CO2processing and their synergism to increase the microbial inactivation in chicken breast meat.E. coliandL. innocuawere inoculated on the chicken breast surface, and the inactivation effects of two different processes, namely SC-CO2and SC-MAPCO2, were compared with or without the addition of REO. Moreover, the impact of the treatments on the superficial color of the meat was considered. The study demonstrated a synergic effect with 1% REO and supercritical CO2for the inactivation ofE. colion chicken meat, while forL. innocua,there was no synergism. Regarding SC-CO2treatment, theE. colireduction was 1.29 and 3.31 log CFU/g, while forL. innocua, it was 1.42 and 1.11 log CFU/g, respectively, without and with the addition of 1.0% of REO. The same amount of REO allowed us to obtain a reduction of 1.3 log CFU/g ofE. coliwhen coupled with SC-MAPCO2. ForL. innocua, no reduction was obtained, either with SC-MAPCO2or together with REO. The synergism of SC-MAPCO2with 1% REO was confirmed for the total psychrophilic bacteria, demonstrating a strong dependence on the microorganism. The color modification induced by the SC-MAPCO2process was lower than the SC-CO2treatment. Overall, this study demonstrated a possible synergism of the technologies which can support the development of innovative methods to improve the safety and shelf-life of chicken breast meat.