Silent information regulator 6 (SIRT6), a class III histone deacetylase, has been revealed to participate in multiple metabolic processes in the liver, and it plays important roles in protecting against ischemia/reperfusion (I/R) injury in multiple organs. In this study, we explored whether SIRT6 is protective against hepatic I/R injury and elucidated the underlying mechanisms. The expression of SIRT6 was significantly decreased during reperfusion compared with the control group. SIRT6-LKO mice exhibited significantly aggravated oxidative stress, mitochondrial dysfunction, inflammatory responses, mitogen-activated protein kinase (MAPK) signaling activation, and apoptosis and autophagy related hepatocyte death compared with control mice. In vitro studies in SIRT6-KO hepatocytes exhibited similar results. In contrast, SIRT6 upregulation alleviated liver damage during hepatic I/R injury. Our study demonstrated for the first time that SIRT6 upregulation effectively protects against hepatic I/R injury. The underlying mechanisms involve the maintenance of oxidative homeostasis and mitochondrial function, which subsequently inhibit the inflammatory responses and MAPK signaling, and finally attenuate apoptosis and autophagy related hepatocyte death. These results suggest that the activation of SIRT6 exerts multifaceted protective effects during hepatic I/R injury, which can provide a novel therapeutic target for hepatic I/R injury.