The article provides a comprehensive analysis of the antioxidant properties of Opuntia dillenii, commonly known as the prickly pear cactus, emphasizing its potential as a natural source of bioactive, health-promoting compounds. Its antioxidant effects are primarily due to polysaccharides, betalains, and polyphenols, which act synergistically to neutralize free radicals and mitigate oxidative stress, a major contributor to cellular damage and the development of chronic diseases. In addition to directly scavenging reactive oxygen species, Opuntia dillenii supports the body’s endogenous defense systems by enhancing the activity of antioxidant enzymes and increasing intracellular glutathione levels. It also lowers lipid peroxidation, as indicated by reduced malondialdehyde levels, thereby safeguarding cellular membranes and tissue integrity. Overall, it highlights the potential of Opuntia dillenii as both a protective agent against oxidative stress and supports in overall health and preventing disorders associated with oxidative damage.