Erythrobacter seohaensis SW-135 was isolated from inter sediments collected from an intertidal zone of the Yellow Sea in Korea. The genome of E. seohaensis SW-135 was sequenced and comprised of one circular chromosome with the size of 2,942,673 bp and DNA G + C content of 61.7%. It was reported that E. seohaensis SW-135 was positive for alkaline phosphatase activity by enzymatic test. Genomic annotation indicated that the genome of E. seohaensis SW-135 had two alkaline phosphatase-encoding genes, phoD and phoX, which products can dephosphorylate phosphoesters to more bioavailable dissolved inorganic phosphorus for microorganisms in the phosphorus limited condition. Comparative genomic analysis of marine Erythrobacter strains revealed that phoD and phoX were widely distributed in these strains, indicating the genus Erythrobacter may play an important role in the marine phosphorus cycle. This study broadens our understandings about ecological roles of the genus Erythrobacter participating in the marine phosphorus cycle, which is rarely investigated previously.