This study aimed to examine the effect of Probax (Lactobacillus acidophilus), thyme (Thymus vulgaris) extract (THM), and their combination on productive performance, rumen function, hematological and blood biochemical components, and immunity of newborn Friesian calves from calving to weaning (105 d) and post-weaning (150 d of age). Total of 20 male Friesian calves at three days of age and 35.07±0.56 kg body weight were allotted into four groups (5 calves/group). In the 1^st group (G1), calves were fed whole cow milk and the starter plus berseem hay after 7 days of age (control). Calves were fed the same control diet supplemented with 50 mg Probax /kg BW (G2), 40 mg of THM/kg BW (G3), and 50 mg of Probax and 40 mg of THM (G4). Growth performance parameters, ruminal VFAs concentration, protozoal count, RBCs, Hb, PCV, and concentration of total proteins, albumin, globulin, glucose, urea, total cholesterol, triglycerides, IgG, IgM, and IgA in blood serum were the highest (P˂0.05), while creatinine concentration, and AST and ALT activities were the lowest in G4. Dietary supplementation of Probax+THM (50 and 40 mg/kg BW) improved growth performance, rumen function, hematology, blood biochemicals, and immunity of Friesian calves at weaning, and at 150 days of age.