The use of non-therapeutic antibiotics as animal feed additives has raised public health concerns due to the increasing resistance of pathogens to antibiotics. It is therefore required to develop safe and effective alternative feed additives to replace non-therapeutic antibiotics. The aim of this study was to assess the effects of the multiherbal compound, KIOM-C, on growth performance and immune response of growing-to-finishing pigs under farm conditions. The experimental trials were performed in a Korean commercial swine growing-to-finishing complex, and a total of 70-day-old 160 pigs were selected. Eighty pigs were treated with KIOM-C at the level of 2 kg/tonne until slaughter age (KT group), while another 80 pigs were not treated with KIOM-C (NT group). All animals were vaccinated against foot-and-mouth disease (FMD) at 60 and 110 days of age. During the trial period, average daily weight gain (ADWG), average daily feed intake (ADFI), feed conversion ratio (FCR), survival rates, and average slaughter ages were measured. The serum concentrations of tumor necrosis factor-a (TNF-α), interferon-γ (IFN-γ), and IgA were also evaluated. In order to evaluate specific humoral immune responses, the foot-and-mouth disease virus (FMDV) serotype O-specific antibody was measured. The ADWG, ADFI, and FCR of the KT group were significantly greater than those of the NT group (p<0.05). Serum concentrations of IgA in the KT group was statistically higher than the NT group. The antibody levels of the KT group against FMDV serotype O was higher than the NT group, and 86.67% of the KT group tested positive for anti-FMDV antibodies. Overall, these findings suggest that KIOM-C improves growth performance and immune response of pigs under growing-to-finishing farm conditions, and implies that the herbal compound may be used as a suitable alternative feed additive.