A new Gram-stain-positive, aerobic, non-motile and rod-shaped actinobacterium, designated O1^T, was isolated from a deep-sea sediment of the Western Pacific Ocean. Strain O1^T showed optimal growth at 30 °C, between pH 6.0 and 8.0, and in the presence of 1–5 % (w/v) NaCl. The predominant menaquinone was MK-8 (H₂), and anteiso-C_15 : 0 and anteiso-C_17 : 0 were the major fatty acids. The diagnostic diamino acid in the cell-wall peptidoglycan was meso-diaminopimelic acid. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and one unknown glycolipid. The DNA G+C content of strain O1^T was 64.9 mol% and the genome size was 4.17 Mb. Based on a similarity search and phylogenetic analysis of the 16S rRNA gene sequence, strain O1^T belonged to the genus Brevibacterium. The values of average nucleotide identity and in silico DNA–DNA hybridization between strain O1^T and its close relatives were well below the thresholds used for the delineation of a new species. On the basis of the morphological and chemotaxonomic characteristics, as well as the genotypic data, it is proposed that strain O1^T represents a novel species of the genus Brevibacterium, for which the name Brevibacterium profundi sp. nov. is proposed. The type strain is O1^T (=JCM 33845^T=MCCC 1A16744^T).