<p>Vagus nerve stimulation (VNS) has demonstrated cardioprotective effects in a variety of cardiovascular diseases, including cardiac ischemia and reperfusion (IR) injury. However, the mechanisms responsible for these effects have not been completely understood. The present work aimed to uncover the potential mechanisms through which VNS confers protection against cardiac IR injury. Rats subjected to cardiac IR injury received electrical VNS through the right cervical vagus nerve. This intervention led to a notable reduction in cardiac dysfunction and injury, as well as decreased cardiac apoptosis, oxidative stress, and inflammation. Moreover, VNS treatment improved mitochondrial biogenesis by upregulating estrogen-related receptor α (ERRα), nuclear respiratory factor 1 (NRF-1), and transcriptional factor A mitochondrial (TFAM). In addition, VNS treatment not only increased the copy number of mitochondrial DNA (mtDNA) and the content of adenosine triphosphate (ATP), but also effectively reduced mitochondrial damage. VNS also upregulated the expression of silent information regulator 1 (SIRT1) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) in IR-injured hearts. Inhibition of either SIRT1 or PGC-1α significantly reversed the effects of VNS on mitochondrial biogenesis and abolished its cardioprotective benefits. Notably, VNS increased the level of acetylcholine (ACh) in IR-injured hearts. Administration of atropine, a muscarinic ACh receptor (mAChR) antagonist, counteracted the effects of VNS on the SIRT1/PGC-1α pathway, mitochondrial biogenesis, and the associated cardioprotective outcomes. These findings suggest that VNS protects against cardiac I/R injury by enhancing mitochondrial biogenesis. This beneficial effect of VNS on mitochondrial biogenesis is attributed to activation of the SIRT1/PGC-1α pathway through the ACh/mAChR axis. Therefore, this research offers fresh perspectives on the mechanisms underlying the cardioprotective effects of VNS.</p>