This study was conducted to investigate the impact of dietary supplementation of cardamom essential oils (CEO) and powdered cardamom seeds (PCS) on the growth performance, plasma biochemistry, haematological characters, immune response and meat acceptability in broilers. In total, 300 day-old male broilers (Ross 308) were allocated to five treatments with six replicates. Dietary treatments included the basal diet as control, CEO-supplemented diets with an inclusion level of 50 (CEO1) or 100 (CEO2) mg/kg, and PCS-supplemented diets with an inclusion level of 3 (PCS1) or 6 (PCS2) g/kg. Feeding PCS1 diet improved (P < 0.05) bodyweight gain and feed conversion ratio (FCR) of broilers during the grower period (11–28 days). Moreover, broilers fed the CEO2 diet had the lowest (P < 0.05) FCR during the whole growth period (0–42 days). Higher bursa index (P < 0.05) was detected in chickens receiving CEO1 and CEO2 diets; additionally, higher spleen index (P < 0.05) was recorded in the CEO1 group at 42 days of age. Haematological parameters including red blood cell, white blood cell, haemoglobin, haematocrit, mean corpuscular volume, mean corpuscular haemoglobin, and mean corpuscular haemoglobin concentration values were not influenced (P > 0.05) by diet. By contrast, CEO1 and CEO2 diets decreased (P < 0.05) the low-density lipoprotein cholesterol (LDL-C) concentrations compared with control diet. Plasma cholesterol level was also lower (P < 0.05) in the CEO1 group at 42 days of age. Sensory evaluation of meat samples indicated no differences (P > 0.05) among treatments for appearance, flavour, texture and overall acceptability. Our results suggest that the CEO2 diet was advantageous compared with control diet with respect to feed efficiency. Moreover, CEO1 had a positive effect on the blood cholesterol profile by decreasing the plasma cholesterol and LDL-C levels.