A Gram-stain-negative, motile, aerobic, rod-shaped bacterium with flagella, designated M3-13T, was isolated from a saline soil in Zhoushan, China. According to phylogenetic analysis based on 16S rRNA gene sequences, strain M3-13T was assigned to the genus Marinobacter with highest 16S rRNA gene sequence similarity of 97.7% to Marinobacter maroccanus LMG 30466T, followed by Marinobacter sediminum R65 T (97.5%) and M. salsuginis SD-14BT (97.2%). Digital DNA-DNA hybridization (DDH) and average nucleotide identity (ANI) were determined to evaluate the genomic relationship between strain M3-13T and M. maroccanus LMG 30466T. Digital DDH estimation (19.8%) as well as ANI (72.98%) proved the dissimilarity of strain M3-13T. Optimal growth of the strain M3-13T was at 28-30 °C and at pH 8.0-8.5, in the presence of 3-6% (w/v) NaCl. The major fatty acids detected in strain M3-13T were C16:1 ω7c/C16:1 ω6c, C16:0, C18:1ω7c/C18:1 ω6c and C12:03-OH, and the predominant respiratory quinone was ubiquinone-9. The major polar lipids included diphosphatidyglycerol, phosphatidylglycerol, phosphatidylethanolamine, one unidentified aminophosphoglycolipid and one unidentified phosphoglycolipid. The DNA G+C content was 56.6%. A phylogenetic analysis based on 16S rRNA gene sequences showed that strain M3-13T belongs to the genus Marinobacter. Based on the polyphasic taxonomic characterization, strain M3-13T is considered to represent a novel species of the genus Marinobacter, for which the name Marinobacter caseinlyticus sp. nov. is proposed (type strain M3-13T = MCCC 1K04560T = KCTC 72043T).