This study investigated the antibacterial effects of plant-based marinades, papaya juice, tomato juice, and their combination, on Staphylococcus aureus in experimentally inoculated chicken breast samples stored at 4°C for 48 h. The control group, treated with distilled water, exhibited a significant increase in S. aureus counts from 6.84±0.11 to 8.74±0.17 log CFU/mL, indicating favorable conditions for bacterial proliferation in untreated chicken breast. Papaya juice marination resulted in a notable reduction in S. aureus counts, achieving a 12.96% decrease at 48 h, which was attributed to bioactive compounds, such as alkaloids and flavonoids. Tomato juice also demonstrated antibacterial effects, with 10.09% reduction in bacterial counts at 48 h, which was linked to its biochemical composition, including phenolic compounds and organic acids. The combined treatment of papaya and tomato juices resulted in the most significant reduction in S. aureus counts, achieving 21.02% decrease after 48 h, suggesting a synergistic effect of the combined bioactive compounds. The results underscore the potential of natural plant-based marinades as effective antibacterial agents for enhancing the safety of poultry products, offering a promising alternative to synthetic preservatives, and catering to consumer demand for natural food additives. Future research should explore the specific mechanisms underlying the observed antibacterial effects and evaluate the efficacy of these treatments against a broader spectrum of foodborne pathogens to further substantiate their applicability in food preservation strategies.