Natural antioxidants, derived from plants, fruits, vegetables, and other natural sources, have been recognized for their potential health benefits. Natural antioxidants have gained widespread attention due to their potential therapeutic properties and their role in protecting human health from oxidative stress-related disorders. Natural antioxidants are crucial for reducing the harmful effects of reactive oxygen species (ROS), free radicals (FRs), and reactive nitrogen species (RNS), which are linked to oxidative stress (OS) and a number of illnesses and ailments. With an emphasis on the division of natural antioxidants into two classes—enzymatic and non-enzymatic—including polyphenols (phenolic compounds and flavonoids) and vitamins, this review explores the production of these reactive species as well as the idea of OS. The human body’s innate antioxidant defence systems are presented, demonstrating the synergy between multiple processes in preventing oxidative damage. The benefits of these natural antioxidants in scavenging free radicals have been extensively discussed and published in previous studies. The health benefits of natural antioxidants, including their anti-inflammatory, anti-cancer, cardiovascular protective, and neuroprotective effects, are also examined. Characteristics that encourage the use of natural antioxidants include their low cost, compatibility with food, and their less adverse effect in the human body. Furthermore, the importance of medicinal plants as antioxidant-rich sources is stressed, opening up new options for health promotion and illness prevention. This comprehensive overview aims to improve understanding and appreciation of natural antioxidants, their mechanisms, applications, and the delicate balance required for their safe and successful usage in health maintenance and disease prevention. Additionally, they support immune function, improve heart health, and reduce the risk of developing chronic diseases. This review summarizes the various natural sources of antioxidants, explores their chemical properties, and examines the scientific evidence supporting their health benefits.