Syzygium triflorum T.T.Hoang, Kim Thanh, S.Tagane & D.H.Cuong, sp. nov., from Kon Chu Rang Nature Reserve, Vietnam, is described and illustrated. The new species is distinguished from related species, Syzygium skiophilum, by its having 4-angled and reddish-grey twigs, oblong leaves with an attenuate apex, less secondary veins of 26–30 pairs, exclusively axillary inflorescences, lanceolate-ovate bracts, sessile flowers, obconical hypanthium (slightly pyriform in flower buds) and more stamens of 18–28. The flowers and fruits were observed in the rainy season, July 2024. This new species grows under a mixed broad-leaved and coniferous forest dominated by Dacrydium elatum and Dacrycarpus imbricatus.