An aerobic, Gram-negative, ovoid to rod-shaped bacterial isolate, strain 81-2(T), was isolated from deep-sea sediment of the Western Pacific Ocean. Strain 81-2(T) was motile, formed faint pink colonies, and was catalase-positive, weakly positive for oxidase and required NaCl for growth. It did not synthesize bacteriochlorophyll a and its DNA G+C content was 62.3 mol%. The 16S rRNA gene sequence of strain 81-2(T) indicated that it was a member of the Roseobacter clade of the class Alphaproteobacteria, with moderate bootstrap support for inclusion in the genus Roseovarius. Its closest phylogenetic neighbour was the type strain of Roseovarius nubinhibens, which shared 95.8 % 16S rRNA gene sequence similarity; strain 81-2(T) was <95.0 % similar to strains of other related species and genera. Phenotypic, chemotaxonomic and phylogenetic data support assignment of this strain to the genus Roseovarius as a representative of a novel species. The name Roseovarius pacificus sp. nov. is proposed, with strain 81-2(T) (=MCCC 1A00293(T)=CGMCC 1.7083(T)=LMG 24575(T)) as the type strain.