Syzygium genus contain several plant species which spread across the world, most of them are having diverse biological activity among which some are reported, and some are not. So, Syzygium genus is a subject of interest to researchers. All Syzygium species are actively studied to find new activity or better dose at which they can be used. This review focuses on various species of genus Syzygium, their phytochemical constituents and their pharmacological activities. Syzygium aromaticum (Clove), Syzygium samarangense (Java apple), Syzygium anisatum (Aniseed tree), Syzygium caryophyllatum (Lilly pilly), Syzygium aqeum (Water apple), Syzygium jambos (Mountain Apple), Syzygium cumini (Java plum), Syzygium australe (Brush cherry), Syzygium luehmannii (Riberry) etc., were mentioned in this review article. Biological activities like anti-diabetic, antioxidant, anti-bacterial, anti-inflammatory, platelet inhibition, hepato-protective were found among plants of Syzygium species. Our present review mentions all the activities, anti-diabetic in detail. We tried to gather cumulative data as per our knowledge, hope it is useful to anyone who is studying or researching about Syzygium. Syzygium cumini is given importance in this review article as it has diverse uses and most of the parts of the plant have their own applications in medical field.