Zicao (Lithospermum erythrorhizon) has been used in clinics as a traditional Chinese medicine for thousands of years. Acetylshikonin (AS) is the main ingredient of Zicao, Xinjiang, China. The objective of this study was to investigate the anti-obesity and anti-nonalcoholic fatty liver disease (NAFLD) efficacy of AS in a model of spontaneous obese db/db mice. Mice were divided into Wild Type (WT) groups and db/db groups, which received no treatment or treatment with 100 mg/kg/day clenbuterol (CL) hydrochloride or 540 mg/kg/day AS by oral gavage for eight weeks. The results provided the evidence that AS prevented obesity and NAFLD including reduction in body weight, food efficiency ratio, serum triglyceride (TG) and free fatty acid (FFA) levels in db/db mice. Administration of AS markedly suppressed the levels of hepatic alanine aminotransferase (ALT), aspartate aminotransferase (AST) and pro-inflammatory cytokines in treated groups when compared with that of db/db groups. Further investigation of the lipid synthesis-related protein using Western blotting revealed that hepatic protein expression of sterol regulatory element-binding protein-1 (SREBP-1), fatty acid synthetase (FAS) and 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) were significantly downregulated by AS treatment. These findings suggest that AS exerts anti-obesity and anti-NAFLD effects through the regulation of lipid metabolism and anti-inflammatory effects.