This study identifies CD38 as a key marker of exhausted CAR-T cells and demonstrates that inhibiting CD38 enzyme activity enhances the cytotoxicity and antitumor efficacy of CAR-T cells by suppressing glycolysis. CD38 inhibition improves memory differentiation and counteracts CAR-T cell exhaustion through the downregulation of CD38-cADPR-Ca²⁺ signaling and activation of the CD38-NAD⁺-SIRT1 axis. The findings suggest that CD38 inhibition could be a potential clinical strategy to enhance the efficacy and persistence of CAR-T cell therapy.This study identifies CD38 as a key marker of exhausted CAR-T cells and demonstrates that inhibiting CD38 enzyme activity enhances the cytotoxicity and antitumor efficacy of CAR-T cells by suppressing glycolysis. CD38 inhibition improves memory differentiation and counteracts CAR-T cell exhaustion through the downregulation of CD38-cADPR-Ca²⁺ signaling and activation of the CD38-NAD⁺-SIRT1 axis. The findings suggest that CD38 inhibition could be a potential clinical strategy to enhance the efficacy and persistence of CAR-T cell therapy.