Lifespan varies within and across species, but the general principles of its control remain unclear. Here, we conducted multi-tissue RNA-seq analyses across 41 mammalian species, identifying longevity signatures and examining their relationship with transcriptomic biomarkers of aging and established lifespan-extending interventions. An integrative analysis uncovered shared longevity mechanisms within and across species, including downregulated Igf1 and upregulated mitochondrial translation genes, and unique features, such as distinct regulation of the innate immune response and cellular respiration. Signatures of long-lived species were positively correlated with age-related changes and enriched for evolutionarily ancient essential genes, involved in proteolysis and PI3K-Akt signaling. Conversely, lifespan-extending interventions counteracted aging patterns and affected younger, mutable genes enriched for energy metabolism. The identified biomarkers revealed longevity interventions, including KU0063794, which extended mouse lifespan and healthspan. Overall, this study uncovers universal and distinct strategies of lifespan regulation within and across species and provides tools for discovering longevity interventions. Display omitted •Distinct molecular mechanisms control lifespan within and across species•Aging effects are reversed by longevity interventions but not by species longevity•Regulation of Igf1 and mitochondrial translation are shared signatures of longevity•Longevity signatures enable the discovery of geroprotectors, such as KU0063794 The analysis of multi-tissue gene expression signatures associated with longevity across mammalian species and their interaction with biomarkers of aging and signatures of lifespan-extending interventions reveals universal and distinct strategies of lifespan regulation within and across species and provides tools for the discovery of longevity interventions in mammals.