A Gram-stain-positive, aerobic, motile, and rod-shaped bacterial strain designated TGS2-1T was isolated from sediment soil in the Nakdong River, Republic of Korea. The optimal growth of strain TGS2-1T was observed at 28°C and pH 7.0 without NaCl supplementation. Strain TGS2-1T revealed antibiosis against various bacteria, including Staphylococcus aureus KCCM 4051, CCARM 3089 (methicillin resistant strains), Enterococcus faecalis KCCM 11814, Escherichia coli KCTC 2443, Candida albicans KACC 7270, and Filobasidium neoformans KCTC 7902. Phylogenetic analyses based on the 16S rRNA gene sequences indicated that strain TGS2-1T belonged to the genus Brevibacillus and shared 93.8-99.7% sequence similarity with Brevibacillus species. Whole-genome sequencing of strain TGS2-1T revealed a genome size of 6.2 Mbp and DNA G + C content of 47.0 mol%. The TGS2-1T genome shared an average nucleotide identity and digital DNA-DNA hybridization of 74.6-93.3% and 18.6-67.1%, respectively, with six related Brevibacillus genomes. The major fatty acid constituents of strain TGS2-1T were anteiso-C15:0 (62.3%) and anteiso-C17:0 (10.8%). Cells of strain TGS2-1T contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, seven unidentified aminophospholipids, and five unidentified lipids. The isoprenoid quinone detected in the strain was menaquinone-7 (MK-7). Based on data obtained from this polyphasic taxonomic study, strain TGS2-1T represents a novel species belonging to genus Brevibacillus, for which the name B. antibioticus sp. nov. is proposed. The type strain is TGS2-1T (= KCCM 90326T = NBRC 113840T = FBCC-B2501).