We describe a new species of pitviper Cryptelytrops honsonensis sp. nov. from Hon Son Island in Rach Gia Bay, Kien Giang Province of southern Vietnam based on it having unique aspects of scalation, body proportions, and color pattern. It is similar to C. venustus in morphology and color pattern and the putative close relationship between these species would corroborate a biogeographical link across southern Indochina seen in a number of other taxa. The presence of this newly discovered insular endemic in Rach Gia Bay and other insular endemics of Rach Gia Bay addressed herein, underscores the understudied nature of these islands and the need for their continued conservation.