Panax ginseng, a foundational herb in traditional East Asian medicine, has been extensively studied for its therapeutic and nutritional properties. Among its bioactive constituents, ginseng polysaccharides (GPs) stand out for their potent antioxidant, anti-inflammatory, and immunomodulatory effects. These polysaccharides, primarily composed of monosaccharides such as glucose, galactose (Gal), and arabinose (Ara), demonstrate promising potential in alleviating oxidative stress and immune suppression. With increasing exposure to ionizing radiation from medical and industrial sources, the demand for effective radioprotective agents has grown. Ionizing radiation induces DNA damage and excessive reactive oxygen species (ROS) production, resulting in oxidative stress and immune dysfunction. Research suggests that GPs mitigate radiation-induced cellular damage by enhancing antioxidant enzyme activity, suppressing inflammatory cytokines, and regulating immune responses. Despite these encouraging findings, further investigations are needed to elucidate their mechanisms of action and optimize their clinical applications. This review provides a comprehensive analysis of the composition, biological activities, and radioprotective mechanisms of GPs, highlighting their potential as functional agents for safeguarding human health against radiation-induced damage.