Mitochondrial reactive oxygen species (mt-ROS) are crucial in infection and immunity. mt-ROS are generated during electron transport chain (ETC) function and play roles in various physiological processes, including immune responses. They are produced in mitochondria, peroxisomes, and other cellular compartments, and their levels are regulated by factors such as redox balance, electron carriers, and antioxidant systems. mt-ROS contribute to immune signaling by modulating pathways involved in T cell activation, phagocytosis, and the formation of neutrophil extracellular traps (NETs). They also play a role in the activation of the NLRP3 inflammasome, which is essential for inflammatory responses. mt-ROS are involved in the regulation of transcription factors like Nrf2 and NF-κB, which control antioxidant responses and immune cell function. However, excessive mt-ROS can lead to oxidative stress and cellular damage, contributing to diseases such as cancer, neurodegeneration, and metabolic disorders. Therapeutic approaches targeting mt-ROS, such as antioxidants and mitochondrial-targeted compounds, are being explored for their potential in treating infectious diseases. The balance of mt-ROS is critical for maintaining cellular homeostasis and effective immune responses.Mitochondrial reactive oxygen species (mt-ROS) are crucial in infection and immunity. mt-ROS are generated during electron transport chain (ETC) function and play roles in various physiological processes, including immune responses. They are produced in mitochondria, peroxisomes, and other cellular compartments, and their levels are regulated by factors such as redox balance, electron carriers, and antioxidant systems. mt-ROS contribute to immune signaling by modulating pathways involved in T cell activation, phagocytosis, and the formation of neutrophil extracellular traps (NETs). They also play a role in the activation of the NLRP3 inflammasome, which is essential for inflammatory responses. mt-ROS are involved in the regulation of transcription factors like Nrf2 and NF-κB, which control antioxidant responses and immune cell function. However, excessive mt-ROS can lead to oxidative stress and cellular damage, contributing to diseases such as cancer, neurodegeneration, and metabolic disorders. Therapeutic approaches targeting mt-ROS, such as antioxidants and mitochondrial-targeted compounds, are being explored for their potential in treating infectious diseases. The balance of mt-ROS is critical for maintaining cellular homeostasis and effective immune responses.