In order to evaluate the effect of diets with Ganoderma lucidum mushroom powder and zinc-bacitracin on growth performance, carcass traits, lymphoid organ weights, and intestinal characteristics in broilers, a total of 600 one-day-old unsexed broilers from Cobb 500 MV × Cobb 500 FF genotype was analyzed for 28 days, following a completely randomized design with three dietary treatments, five replicates and 40 birds per replicate. The dietary treatments consisted of a basal diet (BD) without additives (T0) and the dietary inclusion of 2.5 g/kg of Ganoderma lucidum (T1) and 350 mg/kg of zinc bacitracin antibiotic (T2). The experimental groups did not change (p>0.05) the performance of the broilers. However, G. lucidum powder increased (p≤0.05) the carcass and breast yields (p≤0.05) and decreased the abdominal fat and liver yields (p≤0.05), although with no notable differences with the antibiotic group for the latter organ (liver) (p>0.05). Both additives (G. lucidum and antibiotic) increased breast meat moisture, protein, and redness; however, these treatments reduced L* (lightness), and the zinc-bacitracin reduced breast yellowness (p≤0.05). Likewise, this medicinal mushroom (G. lucidum) increased the relative weight of bursa of Fabricius and the morphometry of the small intestine (p≤0.05), although with no changes for other immune and digestive organs or for the content of cecal lactic acid bacteria (p>0.05). The dietary inclusion with 2.5 g/kg of Ganoderma lucidum powder is recommended to improve breast yield, protein, and colorimetry without affecting performance and cecal traits of fast-growing broilers.