This work reports for the first time the occurrence of Mastacembelus notophthalmus Roberts, 1989 (Synbranchiformes Mastacembelidae) in Bangka Island (Indonesia), more specifically for Bumang Kemuja River, Bangka Induk District, Bangka Belitung Province. This is the southernmost record of this species, extending the species distribution. The new record is about 500 km to the south of the nearest locality in Peninsular Malaysia, about 450 km southeast from the nearest locality in Sumatra, and about 750 km south-west from the nearest locality in Borneo. Therefore, this new record fills an important gap in the geographic distribution of the species, as well as registering the species for an additional island. In addition, we provide here a detailed and updated map on the geographic distribution of this species, based on both published data and material examined. This new record was based on two specimens collected on 22 July 2022. They were identified as M. notophthalmus since they exhibit: dark vertical bar below eye; no reticulate pattern on body, dorsal region mostly dark brown with some yellowish irregular vermiculated marks; ventral region yellowish with incomplete dark brown horizontal stripe; and caudal, dorsal and anal fins yellowish with vertical dark brown bars. In addition, the meristics of both specimens were similar to other records for this species.