Liver injury is a severe clinical complication associated with various diseases or xenobiotics exposure. Hence, finding safe and clinically applicable hepatoprotective agents have great value. Several naturally-derived chemicals have gotten attention for their biological functions. Polysaccharides are bioactive and safe chemicals produced by a variety of microorganisms. Several exciting features, including radical scavenging and antioxidative properties, have been attributed to polysaccharides. Recently we found that the exopolysaccharide derived from Pentoea sp. BCCS 001 GH (Pentoan exopolysaccharide; PEPS) revealed significant antioxidant and radical scavenging properties in an in vitro model. Hence, the current study was designed to evaluate the in vivo hepatoprotective effects of PEPS. Bile duct ligated (BDL) rats received PEPS (0.05 and 0.1% w: v in drinking water), and serum biomarkers of liver injury, liver tissue histopathological alterations, and hepatic markers of oxidative stress were monitored. Severely elevated serum biomarkers of liver injury and histopathological changes, including inflammatory cell infiltration, necrosis, bile duct proliferation, and tissue fibrosis, were evident in BDL animals. Moreover, a significant amount of reactive oxygen species, increased level of lipid peroxidation, and defects in tissue antioxidant capacity were apparent in BDL rats. It was found that PEPS significantly improved liver function, blunted hepatic pathological changes, and counteracted oxidative stress in the liver tissue. The radical scavenging and antioxidant properties of PEPS seem to play a fundamental role in its hepatoprotective properties.