Antioxidants and oxidants are essential for preserving the delicate equilibrium of animal health. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are the two main oxidant types that are produced spontaneously as byproducts of metabolic processes. Even while these molecules are essential for a number of physiological functions, including immunological response and cell signaling, their overproduction can result in oxidative stress, which can damage lipids, proteins, and DNA. This oxidative imbalance has been connected to a wide range of animal diseases, including metabolic disorders, inflammatory issues, and degenerative diseases. Similarly, antioxidants are essential defense mechanisms that neutralize excess oxidants and stop oxidative damage. They include both enzymatic systems (like superoxide dismutase and catalase) and non-enzymatic substances (such vitamins C and E and glutathione). Recent research has demonstrated the value of dietary antioxidants and supplementation in improving animal health, raising productivity, and reducing the effects of environmental stressors. This chapter explores the dynamic interplay between oxidants and antioxidants, focusing on the molecular mechanisms, biological significance, and health implications for animals. Further, it also covers ways to reduce oxidative stress by nutritional and pharmacological therapies to improve the health and performance of many animal species.