Trigonelline, a natural alkaloid structurally related to nicotinic acid, is reduced in serum levels in individuals with sarcopenia and correlates positively with muscle strength and mitochondrial oxidative phosphorylation in skeletal muscle. This study demonstrates that trigonelline incorporates into the NAD⁺ pool, increasing NAD⁺ levels in *Caenorhabditis elegans*, mice, and primary myotubes from healthy and sarcopenic individuals. Trigonelline does not activate GPR109A but is metabolized via the nicotinate phosphoribosyltransferase/Preiss–Handler pathway. In *C. elegans*, trigonelline improves mitochondrial respiration and biogenesis, reduces age-related muscle wasting, and increases lifespan and mobility through an NAD⁺-dependent mechanism involving sirtuins. Dietary supplementation with trigonelline in male mice enhances muscle strength and prevents fatigue during aging. These findings identify trigonelline as a potential nutritional strategy to boost NAD⁺ levels and improve age-associated muscle decline.Trigonelline, a natural alkaloid structurally related to nicotinic acid, is reduced in serum levels in individuals with sarcopenia and correlates positively with muscle strength and mitochondrial oxidative phosphorylation in skeletal muscle. This study demonstrates that trigonelline incorporates into the NAD⁺ pool, increasing NAD⁺ levels in *Caenorhabditis elegans*, mice, and primary myotubes from healthy and sarcopenic individuals. Trigonelline does not activate GPR109A but is metabolized via the nicotinate phosphoribosyltransferase/Preiss–Handler pathway. In *C. elegans*, trigonelline improves mitochondrial respiration and biogenesis, reduces age-related muscle wasting, and increases lifespan and mobility through an NAD⁺-dependent mechanism involving sirtuins. Dietary supplementation with trigonelline in male mice enhances muscle strength and prevents fatigue during aging. These findings identify trigonelline as a potential nutritional strategy to boost NAD⁺ levels and improve age-associated muscle decline.