Updated project metadata. Probiotics play important role in maintaining the health and extend longevity in their host. Previous studies reported several live probiotic bacteria in enhancing longevity and improving diverse feature of the host’s health. In this study, we reported a new potential heat- killed probiotic bacterium Levilactobacillus brevis strain MRKAK9 improved longevity and different features of healthy aging, including age-associated physical activity, improved resistance to biotic and abiotic stress in C. elegans. The mechanistic investigations showed that heat-killed strain MRKAK9 promoted longevity and healthy aging by downregulating insulin-signaling pathway resulting in improved proteostasis, autophagy and preserving lysosomal functionality in C. elegans. Heat-killed strain MRKAK9-mediated downregulation of insulin signaling pathway was regulated by the miRNA mir-243, suggesting that mir-243 partially involved in enhancing longevity of C. elegans. Additionally, the structural component exopolysaccharide of the strain heat-killed MRKAK9 also downregulated insulin- signaling mechanisms, increased the expression of genes involved in proteostatsis, autophagy as well as improved expression of mir-243. This study indicates that heat-killed strain MRKAK9 improves longevity and healthy aging, suggesting its candidature as a novel postbiotic.