The octocoral Nanipora kamurai is the fifth species of octocoral described with an aragonite skeleton. So far, it has only been known from a single location in Okinawa, Japan. Here, we report on the second recorded location of the genus Nanipora, in the Gulf of Thailand, where its colonies were found in relatively high densities. A total of 143 separate Nanipora colonies were counted in transects on a coral reef at Koh Tao, Thailand. They were found living on dead coral skeletons and on the shell of a living Tridacna squamosa clam. Phylogenetic analyses of cytochrome oxidase subunit 1 (COI) and mitochondrial mismatch repair protein (mtMutS) sequences showed that they belong to N. kamurai or to a close relative of this species. Additionally, a symbiotic relationship with Symbiodinium was observed for the first time in Nanipora, confirmed by sequences of the internal transcribed spacer region of ribosomal DNA (ITS-rDNA) of the dinoflagellate.