Copaifera sp. is a native tree in the Amazon region. Copaiba oleoresin has components such as sesquiterpenes, which have anti-inflammatory and antioxidant potential. Liver cirrhosis is the end stage of liver disease with limited therapeutic options. We aimed to evaluate the effect of copaiba oleoresin supplementation on the liver of animals with thioacetamide (TAA)-induced cirrhosis. For the induction of liver cirrhosis, 100 mg/kg of TAA was administered intraperitoneally twice a week for 8 weeks. A total of 200 mg/kg/day of copaiba oleoresin was administered via gavage for the same period. Copaiba oleoresin supplementation improved cirrhosis-associated cachexia by increasing weight gain and body fat. In addition, copaiba oleoresin attenuated systemic inflammation, as shown by the decrease in the circulating C-reactive protein. In the liver, the copaiba oleoresin decreased carbonyl proteins and increased IL-10 compared with TAA-treated rats. TAA groups demonstrated increased SOD, catalase, GST, and GSH activity in the liver. In conclusion, the supplementation of copaiba oleoresin demonstrated a beneficial systemic effect in alleviating cirrhotic cachexia and antioxidant and anti-inflammatory action in the liver. However, it failed to improve the serological and histological markers of liver damage, which could be associated with the advanced stage of the disease.