Island ecosystem is a fragile ecosystem affected by an ocean climate, which resulting different microclimates, floristic composition and unique habitats. The island’s insularity resulted in the unique composition of animal species, especially reptiles which depend most on the microclimate. Hence, a study on reptile diversity was carried out in Pulau Tinggi, Mersing, Johor from February to October 2019. A previous survey of reptile diversity in Pulau Tinggi was conducted in 2003 and 2006, which recorded 13 and 17 species, respectively and there is an urgent need to update these data. This study used the Visual Encounter Survey (VES) and drift-fenced pitfall traps as the primary sampling methods. 21 species were recorded, which comprise eight families. The Scincidae family recorded the highest number of species, which is five. Meanwhile, Viperidae and Varanidae reported the lowest number of species recorded, one species, respectively. 13 species were reported as new records for Pulau Tinggi, resulting in updated reptile diversity in Pulau Tinggi currently to 32 species based on a comparative literature review with previous studies. These new records indicate that extensive and intensive studies are needed to determine the reptilian diversity in Pulau Tinggi for conservation and management purposes.