IRW (Ile-Arg-Trp) is an angiotensin converting enzyme (ACE) inhibitory peptide identified from egg protein ovotransferrin. Given its role also as an antioxidant, the aims of this work were to investigate whether IRW exerts its protective effect against oxidative stress by inhibiting intracellular ROS accumulation and blocking ROS activated mitochondria-mediated cell apoptosis pathway. Adding 200 μM H₂O₂ to cells led to decreased cell viability while increased (ROS) formation. However, IRW significantly inhibited H₂O₂-induced cytotoxicity and ROS production. Flow cytometry was used to assess the cell apoptosis and the mitochondrial membrane potential. Pretreatment with IRW decreased cell apoptosis while elevated the mitochondrial membrane potential compared to H₂O₂ treated cells. Furthermore, IRW reduced the levels of caspase-9 and caspase-3 and thus improved cell survival. The results demonstrate that IRW can significantly protect Caco-2 cells against oxidative stress by inhibiting intracellular ROS accumulation and blocking the ROS activated mitochondria-mediated cell apoptosis pathway.