This study investigated dietary supplementation with ( ATCC19659 on growth performance, biochemical indices, intestinal morphology, and cecum microflora in broiler chicks. A total of 600 Arbor 1-day Acres broilers of either sex were allotted to 5 treatments: chicks were fed a corn- and soybean-based diet (CON); chicks were fed basal diet containing 500 mg ZnB/kg (ZnB); chicks were fed basal diet containing 1 × 10 CFU/g feed of BS-ATCC19659 (BS-1); chicks were fed basal diet containing 3 × 10 CFU/g feed of BS-ATCC19659 (BS-3); and chicks were fed basal diet containing 5 × 10 CFU/g feed of BS-ATCC19659 (BS-5). Each treatment comprised 6 replicates with 20 birds for each replicate pen. Chicks in the BS-5 and BS-3 groups had higher body weight at the 21 and 42 days and average daily gain from 1 to 21 days than that in the CON group ( < 0.05). Chicks in the BS-5 and ZnB groups had higher serum antioxidant activities and immunity response than those in the CON group ( < 0.05). Compared with the CON group, the liver mRNA abundance of , , , , , , and of chicks in three groups and the ileum villus length (μm) of chicks in BS-3 and ZnB groups was increased ( < 0.05). Compared with the CON group, the villus height-to-crypt depth ratio of the ileum of chicks in the BS-5 and BS-3 groups and the crypt depth and villus height-to-crypt depth ratio of the jejunum in the BS-5 and ZnB groups were increased ( < 0.05). The abundance of the phyla in the cecum decreased in response to treatment with both -ATCC19659 and ZnB groups ( < 0.05). Compared with the CON group, the cecum abundance of genera ( ), , and ( phylum) in three groups were increased ( < 0.05); The abundance of genus reduced in the BS-3 group ( < 0.05). Compared with the CON group, the cecum abundance of genus in ZnB and BS-5 groups was decreased ( < 0.05) of broilers. Generally, ATCC19659 as feed additive positively affected growth performance, immunity response, and cecal microflora of broilers.