A Gram-stain negative, non-motile, brilliant yellow and non-spore forming, coccoid- or short rod-shaped bacterium, designated strain KSK16Y-1^T, was isolated from surface-sterilised leaf of Rhizophora stylosa collected from Shankou Mangrove Nature Reserve, Guangxi Zhuang Autonomous Region, China. Genome of strain KSK16Y-1^T is 4.93 Mb with 68.1% DNA G + C content and encoded 4359 predicted proteins, 4 rRNAs, 45 tRNAs and 4 ncRNA. Comparative 16S rRNA gene sequence analysis showed that the strain KSK16Y-1^T has 98.1%, 97.9% and 96.9% 16S rRNA gene similarities with Jiella aquimaris JCM 30119^T, J. endophytica CBS5Q-3^T and J. pacifica 40Bstr34^T, respectively. Whole-genome comparisons between strain KSK16Y-1^T and J. aquimaris 22II-16-19i, J. endophytica CBS5Q-3^T, J. pacifica 40Bstr34^T, using average nucleotide identity (ANI) values (< 82.0%) and digital DNA-DNA hybridization (dDDH) values (< 25.1%), confirmed low genome relatedness. Strain KSK16Y-1^T grew at 20–30 °C (optimum, 30 °C), pH 6.0–11.0 (optimum, pH 6.0–7.0) and with 0–10% (w/v) NaCl (optimum, 0–2%). Cell wall contained meso-diaminopimelic acid and the major fatty acid was C_18:1ω7c. The polar lipid profile consists of phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, one unknown phospholipid, one unknown aminolipid, one unknown aminophospholipid and four unidentified lipids. The predominant respiratory quinone is ubiquinone-10 (Q-10). The polyphasic characterization indicated that strain KSK16Y-1^T represents a novel Jiella species. The name Jiella mangrovi sp. nov., type strain KSK16Y-1^T (= CGMCC 1.18745^T = JCM 34332^T) is proposed.