Purpose <p>Acute liver injury (ALI) is a burden on public health conferring a strong correlation with morbidity and mortality. Thus, this work was carried out to reveal the possible mechanisms by which policosanol can alleviate thioacetamide (TAA)-induced ALI.</p> Methods <p>TAA was injected once (500 mg/kg, i.p.) in male Sprague Dawley rats) 8 rats/group, 8–10 weeks old, 180–200 g). Two groups of rats were pretreated orally twice with two different doses of policosanol (20 and 50 mg/kg), 24 h and 1 h prior to TAA injection. Animals were sacrificed 24 h after TAA injection. Serum and hepatic tissues were sampled to assess the underlying mechanism.</p> Results <p>Policosanol improved liver architecture, restored liver integrity markers, decreased malondialdehyde (MDA) levels and increased antioxidant defenses by increasing both reduced glutathione (GSH) and total antioxidant capacity (TAC). The higher dose of 50 mg/kg was more effective and was selected for further mechanistic exploration. Policosanol alleviated inflammation by affecting the transcriptional factor nuclear factor-kappa B (NF-κB) which subsequently reduced pro-inflammatory cytokine interleukin-1β (IL-1β) levels and the protein expression of IL-6. These effects could be attributed to its regulation of hepatic levels of mitogen-activated protein kinase (MAPK), increasing both Sirtuin 1 (SIRT1) and peroxisome proliferator-activated receptor-γ (PPAR-γ) levels. Conclusion, policosanol effectively countered TAA-induced ALI by reducing oxidative stress and inflammation through regulation of MAPK, SIRT1, PPAR-γ, and NF-κB.</p>