Aluminum oxide nanoparticle (Al2O3NP) is a common Life-threatening environmental pollutant. It performs its toxic action via induction of lipid peroxidation, protein oxidation, disruption of Redox system and finally cellular death. Therefore, this study aimed to find out whether cinnamon may protect rats from liver damage caused by Al2O3NP. Forty male Wister albino rats were categorized into four Similar groups at random. The control group was given Milli-Q water orally for 28 days, cinnamon group was given 200 mg/kg/day of cinnamon disintegrated in Milli-Q water orally for 28 days, Al2O3NP group was given 100 mg/kg/day of Al2O3NP disintegrated in Milli-Q water orally for 28 days. Al2O3NP + cinnamon group was given 100 mg/kg/day of Al2O3NP, and 200 mg/kg/day of cinnamon dissolved in Milli-Q water orally for 28 days. Al2O3NP exposed rats' serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and total cholesterol (TC) dramatically increased. Moreover, decreased glutathione reduced (GSH), while malondialdehyde (MDA) and hydrogen peroxide (H2O2) levels in the hepatic tissues significantly increased. Histopathological examination of liver sections confirmed this hepatic damage where hepatic degeneration and necrosis were observed. Cinnamon co-administration was effective in restoring the parameters to normal and reducing hepatic injury in Al2O3NP-intoxicated rats. As a result, our findings indicate that cinnamon may have protective effects due to its antioxidant defense systems.