Abstract: Viral myocarditis (VMC) is one of the most common acquired heart diseases in children and teenagers. However, its pathogenesis is still unclear, and effective treatments are lacking. This study aimed to investigate the regulatory pathway by which exosomes alleviate ferroptosis in cardiomyocytes (CMCs) induced by coxsackievirus B3 (CVB3). CVB3 was utilized for inducing the VMC mice model and cellular model. Cardiac echocardiography, left ventricular ejection fraction (LVEF) and left fractional ventricular shortening (LVFS) were implemented to assess the cardiac function. In CVB3-induced VMC mice, cardiac insufficiency was observed, as well as the altered levels of ferroptosis-related indicators (GPX4, GSH, and MDA). However, exosomes derived from human umbilical cord mesenchymal stem cells (hucMSCs) could restore the changes caused by CVB3 stimulation. Let-7a-5p was enriched in hucMSCs-exo, and the inhibitory effect of hucMSCs-exo^{let-7a-5p mimic} on CVB3-induced ferroptosis was higher than that of hucMSCs-exo^{mimic NC}. SMAD2 increased in the VMC group, while the expression of ZFP36 decreased. Let-7a-5p was confirmed to interact with SMAD2 mRNA, and the SMAD2 protein interacted directly with the ZFP36 protein. Silencing SMAD2 and overexpressing ZFP36 inhibited the expression of ferroptosis-related indicators. Meanwhile, the levels of GPX4, SLC7A11, and GSH were lower in the oe-SMAD2+let-7a-5p mimic than in the oe-NC+let-7a-5p mimic groups, while those of MDA, ROS, and Fe²⁺ increased. In conclusion, these data showed that ferroptosis could be regulated by mediating SMAD2 expression. Exo-let-7a-5p derived from hucMSCs could mediate SMAD2 to promote the expression of ZFP36, which further inhibited the ferroptosis of CMCs to alleviate CVB3-induced VMC.