This study investigated the effects of supplementing broiler chicken diets with Viscum album leaf powder (VLP) on various physiological parameters under heat stress conditions. Four dietary treatments were implemented, including a negative control (Diet 1), a positive control with vitamin C supplementation (Diet 2), Diets 3 and 4 contained a supplement of 2.5 and 5.0 g of VLP /kg, respectively. Haematological parameters, serum protein levels, and meat oxidative status were assessed. Results showed that diets supplemented with Viscum album leaf powder (Diets 3 and 4) significantly increased packed cell volume and haemoglobin concentration compared to the birds on diet 1. Additionally, red blood cell counts were higher in birds fed Diet 4 compared to those in Diet 1. The glucose concentration of birds in Diet 4 was similar (P>0.05) to those on Diets 2 and 3 but lower than those fed Diet 1. The serum aspartate aminotransferase of broiler chickens in Diet 3 was similar (P>0.05) to those in Diets 1, 2, and 4, while the aspartate aminotransferase of birds in Diets 2 and 4 was lower (P<0.05) than those in Diet 1. Alanine aminotransferase and cholesterol levels of birds on Diets 2, 3, and 4 were lower (P<0.05) than those on Diet 1. Furthermore, supplementation with Viscum album leaf powder led to higher meat glutathione peroxidase and catalase levels, lower lipid peroxidation levels, and reduced meat cholesterol levels compared to those fed diet 1. In conclusion, supplementation with 2.5 g/kg Viscum album leaf powder effectively improved haematological indices, serum protein levels, and meat oxidative status while reducing meat cholesterol levels under heat stress conditions in broiler chickens.