Abstract: To study the immunomodulatory effects and safety of an antioxidant supplement composed primarily of Haematococcus pluvialis, selenium-enriched yeast, bee pollen extract, and vitamin E. Three different dosages (0.1, 0.2, and 0.4 g/kg bw) were administered via gavage once daily for 30 days in mice. The impact of this antioxidant supplement was observed on various parameters, including spleen index, thymus index, splenic lymphocyte transformation activity, delayed-type hypersensitivity, antibody-producing cell levels, hemolytic complement 50 (HC₅₀), carbon clearance rate, phagocytic activity of macrophages, and natural killer cell activity. The potential carcinogenicity of the test materials, and their genotoxic effects on cells and the reproductive system were assessed through the Ames test, bone marrow micronucleus assay, and mouse sperm abnormality test, respectively. Subacute toxicity was investigated through a 30 day feeding trial. Results showed that compared to the control group, the middle and high-dosage groups exhibited significant increase in OD difference by 10.32% (P<0.05) and 14.29% (P<0.01), respectively. It indicated that the antioxidant supplement promoted splenic lymphocyte proliferation and transformation capacity in mice. In the high-dosage group, the difference in ear swelling between the left and right ears increased by 8.02% (P<0.05), and the number of antibody volumes increased by 22.12% (P<0.05). It suggested that the antioxidant supplement significantly improved delayed-type hypersensitivity and antibody-producing cell capacity. Importantly, no acute toxicity, genotoxicity, or subacute toxicity were observed. It is demonstrated that the antioxidant supplement is safe for consumption and significantly enhances immunity.