A novel marine bacterial strain designated JAMH 011(T) was isolated from the cold-seep sediment in Sagami Bay, Japan. Cells were Gram-stain-negative, rod-shaped, non-spore-forming, aerobic chemo-organotrophs and motile by means of a single polar flagellum. Growth occurred at temperatures below 31 °C, with the optimum at 25 °C. The major respiratory quinone was Q-10. The predominant fatty acid was C18 : 1ω7c. On the basis of 16S rRNA gene sequence analysis, the isolated strain was closely affiliated with members of the genus Shimia in the class Alphaproteobacteria, and the 16S rRNA gene sequence similarity of the novel isolate with the type strain of the closest related species, Shimia haliotis WM35(T), was 98.1%. The DNA G+C content of the novel strain was 57.3 mol%. The hybridization values for DNA-DNA relatedness between strain JAMH 011(T) and reference strains belonging to the genus Shimia were less than 9.4 ± 0.7%. Based on differences in taxonomic characteristics, the isolated strain represents a novel species of the genus Shimia, for which the name Shimia sagamensis sp. nov. is proposed. The type strain is JAMH 011(T) ( = JCM 30583(T) = DSM 29734(T)).