Haematococcus lacustris is a green unicellular alga known for its diverse beneficial carotenoids, such as β-carotene, canthaxanthin, and astaxanthin, with varying compositions at different morphological stages. Each carotenoid might affect the lifespan of Caenorhabditis elegans by inhibiting reactive oxygen species (ROS). C. elegans were fed with carotenoids either using the Escherichia coli OP50 that had pre-consumed commercial carotenoids and the optimal Haematococcus medium containing a dissolved carotenoid. As a result, lifespan of C. elegans was extended by 1.3 times. Three carotenoids indirectly protected C. elegans against ROS by upregulating the expression of superoxide dismutase (maximum 9.8 times) and catalase (maximum 2.5 times). Carotenoids reduced the concentration of malondialdehyde, a product of lipid peroxidation induced by ROS, by 11.2 times in C. elegans. These results suggest that carotenoids could induce antioxidation effect and prolong the lifespan of C. elegans. And H. lacustris could be the most versatile producer of carotenoids.