This study was conducted to evaluate the effects of processed apple peel waste (APW), alone or in combination with an enzyme, as a natural antioxidant on broiler chickens under heat stress. A total of 360 unsexed, 28-day-old broilers were assigned to 6 dietary treatments with four replicates (15 broilers per pen). The experiment consisted of a 3 × 2 factorial arrangement with three levels of apple peel waste (0, 50 or 100 g/kg of diet) and two levels of enzyme (0 or 500 mg/kg, ZY Multi(®)). Inclusion of 100-g APW/kg of diet decreased broiler weight gain at 42 days of age. Inclusion of 50 and 100-g APW/kg of diet increased gizzard and small intestine weights. Feeding 50 and 100-g APW/kg increased high-density lipoprotein (HDL) cholesterol and decreased low-density lipoprotein (LDL) cholesterol and malondialdehyde in blood serum at 49 days of age. At 49 days of age, apparent ileal protein digestibility was reduced when 50 and 100-g APW/kg were used in the diet. This study showed that feeding APW up to 50 g/kg from 28 to 49 days of age increased HDL cholesterol and decreased LDL cholesterol in serum and had no adverse effect on broiler performance.