This study was designed to determine whether copaiba oleoresin inhibits sucrose-induced obesity and its hepatic complications. Thus, male Wistar rats were divided into three groups (n = 6 each group): control (C), high-sucrose diet (HSD) and HSD with copaiba oleoresin (200 mg/kg/day by gavage). After 8 weeks of treatment, oxidative stress parameters such as catalase, superoxide dismutase (SOD), reduced glutathione (GSH), glutathione S-transferase (GST), vitamin C (Vit C), carbonylated protein and lipid peroxidation were evaluated in the liver. Also, steatosis was determined. HSD rats presented obesity, which was characterized by an increased body weight and adiposity index. Obesity was associated with steatosis and a reduced level of hepatic GST, SOD and vitamin C. Copaiba oleoresin supplementation in HDS group was able to prevent obesity development and hepatic steatosis, and was associated to higher levels of GST, SOD and Vit C in the liver. Also, copaiba oleoresin decreased hepatic carbonylated protein levels. In conclusion, copaiba oleoresin prevented obesity development and improves hepatic redox system and steatosis. These results provided new insights that copaiba oleoresin may be a therapeutic natural compound feasible and beneficial for liver protection in diet-induced obesity.