Aging is characterized by oxidative stress and immune function impairment, and is associated with increased morbidity. Cannabidiol (CBD) has anti-oxidant properties, but its role in aging has been scarcely studied. This work aims to test the effect of CBD on the redox state and immunity during aging in rats. In this study, 15-month-old male Long Evans rats received 10 mg/kg b.w/day of CBD in their diet for 10 weeks and were compared with same-age control and 2-month-old rats serving as a young control group, both following a standard diet. After treatment, they were sacrificed, and the spleen, thymus, and total blood cells were collected. Redox parameters such as glutathione reductase and peroxidase activities, reduced (GSH) and oxidized (GSSG) glutathione concentration, GSSG/GSH ratio, and lipid peroxidation were evaluated. Moreover, immune functions (chemotaxis, natural killer activity, and lymphoproliferation) were analyzed in the spleen. Results show that the 15-month-old control rats exhibited increased oxidative stress and immunosenescence compared to the 2-month-old rats. However, the CBD-treated animals showed higher anti-oxidant defenses, lower oxidants in the spleen, thymus, and blood cells, and better immunity in the spleen than the corresponding age-matched controls. Therefore, CBD administration neutralizes oxidative stress and improves immunity, suggesting it is a strategy for achieving healthy aging.