Marinobacterium aestuarii ST58-10T was identified as a benzene-degrading aerobic bacterium isolated from estuarine sediment in the Republic of Korea. The genome of strain ST58-10T was found to be composed of a single circular chromosome (5,191,608 bp) with a G+C content of 58.78% and harboring 4,473 protein-coding genes. The assembled sequence data will help elucidate potential metabolic pathways and mechanisms responsible for the hydrocarbon-degrading ability of M. aestuarii ST58-10T.