The current study evaluated the effects of parsley essential oil on broiler growth performance, carcass features, liver and kidney functions, immunity and antioxidant activity, and lipid profile. A total of 160 unsexed 7-day broiler chicks (Cobb500) were distributed into five groups; each group contained five replicates with eight birds each. The treatments were (1) basal diet (no additive, T1), (2) basal diet + 0.5 mL parsley essential oil/kg (T2), (3) basal diet + 1 mL parsley essential oil/kg (T3), (4) basal diet + 1.5 mL parsley essential oil/kg (T4), and (5) basal diet + 2 mL parsley essential oil/kg (T5). According to GC-MS analysis, parsley oil contains D-limonene, hexadecanoic acid, α-cyclocitral, globulol, α-pinene, myristicin, cryophyllene, bergapten, α-chamigrene, etc. The current results indicated that the most abundant molecules in parsley oil were D-limonene (18.82%), oleic acid (14.52%), α-cyclocitral (11.75%), globulol (11.24%), α-guaiene (7.34%), apiol (5.45%), and hexadecanoic acid (4.69%). Adding parsley essential oil to the broiler diet quadratically increased body weight (BW) during 1–3 weeks of age. The T5 group recorded the highest value (869.37 g) of BW in comparison to other treatments and the control group. The cholesterol, triglyceride, low-density lipoprotein (LDL) cholesterol, and total immunoglobulin, including immunoglobulin G (IgG) and immunoglobulin M (IgM) levels in the birds fed parsley essential oil were not affected. The T3 group recorded the highest value (159 ng/mL) of superoxide dismutase (SOD) and the lowest value (2.01 ng/mL) of malondialdehyde (MDA) when compared to the control and other treatment. In conclusion, we recommend using parsley oil at levels of 1 mL/kg diet of broiler chicks.