A Gram-stain-negative bacterium, designated YJ20T, was isolated from rhizosphere soil of a spinach farmland at Shinan in Korea. Strain YJ20T was found to be aerobic, non-motile rods which can grow at 10-33 °C (optimum, 28 °C), at pH 6.5-8.5 (optimum, pH 6.5-7.5) and in the absence of NaCl. The 16S rRNA gene sequence analysis showed that strain YJ20T belongs to the genus Altererythrobacter with moderate sequence similarities to Altererythrobacter dongtanensis KCTC 22672T (96.8%), Altererythrobacter soli MN-1T (96.6%) and Altererythrobacter xinjiangensis S3-63T (96.5%). The phylogenomic analysis based on the whole-genome sequence demonstrated that strain YJ20T formed a distinct phyletic line with Altererythrobacter soli MN-1T and Altererythrobacter salegens XY-R17T showing average nucleotide identity (ANI) values of 79.4 and 77.5%, respectively. The predominant ubiquinone was identified as Q-10, and the major fatty acids were C17:1 ω6c, C18:1 ω7c and C15:0 2-OH. The major polar lipids were identified as diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidycholin, sphingoglycolipid, an unidentified glycolipid, an unidentified phospholipid and an unidentified lipid. The G+C content of the genome was determined to be 66.3 mol%. On the basis of phenotypic, chemotaxonomic properties and phylogenetic and phylogenomic analyses in this study, strain YJ20T is considered to represent a novel species in the genus Altererythrobacter, for which the name Altererythrobacter segetis sp. nov. is proposed. The type strain is YJ20T (= KACC 19554T = NBRC 113199T).