This study was performed to determine the chemical composition, antioxidant and antibacterial activity of Syzygium polyanthum essential oil. The essential oil was extracted from the leaves by hydro distillation method. A total of 34 compounds were identified using GC-MS, representing 93.87% of the overall composition. The leaf essential oil of S. polyanthum was composed largely of the monoterpene hydrocarbons and sesquiterpene hydrocarbons. The main components of the oils were α- pinene (30.88%) as major compounds followed by octanal (18.30%) and α-caryophyllene (6.22%). Antioxidant activities of the essential oils were evaluated using three different assay; DPPH free radical scavenging, β-carotene bleaching and ferrous-ion chelating. Results showed that the oil exhibited a potential antioxidant activity. The antibacterial activity of the essential oil was tested using disc diffusion method against three Gram-positive and three Gram-negative bacterial strains and the minimum inhibitory concentration (MIC) was determined. The oil was found to be more active against Gram-negative bacteria than Gram-positive bacteria. This study concludes that the essential oil from S. polyanthum possess bioactivity potential for purpose of development of new natural-based products.