Saccharomyces cerevisiae fermentation products (SCFP) can potentially promote gastrointestinal growth and immunity in young livestock. However, reports within the existing literature on the effects of SCFP supplements on calves have been inconsistent; therefore, we perform the following experiments to resolve the inconsistencies. A total of 22 Holstein calves [10 d after birth, BW = 48.93 ± 3.99 kg (mean ± SD)] were assigned randomly into two groups, namely the control group (CON) and SCFP group, each having 11 replicas. The calves in the CON were fed a basal diet, while the SCFP group was fed the basal diet supplemented with 5g/head/d SCFP (NutriTek, Diamond V, Cedar Rapids, IA52404, United States) incorporated into feed. All the calves were regularly fed thrice daily at 08:00, 14:30, and 21:00 and had free access to water. A 5-day adaptation phase was followed by a 45-day experimental period. The results showed that compared to the CON, at the end of the d-45 trial, the body weight was significantly greater in the SCFP group (p < 0.05), and during the 1-45 days, the ADG was higher (p < 0.05). The FCR in the 30-45 days SCFP group was higher (p < 0.05). Furthermore, the apparent digestibility of DM, CP, EE, ADF, Ca, and P were significantly increased in the SCFP group, except for NDF (p < 0.05). The concentration of GH and IGF-1 in serum showed a tremendous increase (p < 0.05) with SCFP supplementation on d 15 and d 45. On d 15, SCFP supplementation significantly increased the serum IgA contents (p < 0.05). Notably, on d 15 and d 45, the serum concentrations of IL-1β, IL-6, and TNF-α reduced (p < 0.001). Moreover, the Actinobacteriota in the SCFP group were significantly lower than those in the CON group (p = 0.034). SCFP significantly increased the abundance of Butyricimonas, Parabacteroides, and Ruminococcus. The differences among sob, Chao1, and PD-tree groups were statistically significant (p < 0.05). In conclusion, these results demonstrate that SCFP supplementation improved ADG, apparent digestibility and serum hormone, enhanced immunity, and regulated gut microbiota, thereby jointly promoting the growth of pre-weaning calves.