Corals live with complex assemblages of microbes including bacteria, the dinoflagellate Symbiodiniaceae, fungi and viruses in an ecological unit termed the coral holobiont. These coral-associated microorganisms play an important role in their host fitness and survival. Here, we investigate the structure and diversity of algal and bacterial communities associated with five common Indo-Pacific coral species (Pocillopora spp., Pavona decussata, Pavona frondifera, Porites lutea and Platygyra sinensis) across three reef sites in the Gulf of Thailand, using full-length 16S genes and internal transcribed spacer (ITS) sequences generated from Pacific Biosciences (PacBio) circular consensus sequencing. While the dinoflagellate communities associated with P. lutea were dominated with Symbiodiniaceae genus Cladocopium, the other four coral hosts were associated mainly with members of Durusdinium genus, suggesting that host species was one of the underlying factors influencing the structure and composition of dinoflagellate communities associated with corals in the Gulf of Thailand. Alphaproteobacteria dominated the microbiome of Pocillopora spp. while P. frondifera and P. lutea were associated primarily with Gammaproteobacteria. The degree of influence that host identity had on the algal and bacterial assemblage structure and composition varied among coral species, with P. lutea exhibiting a strong influence on both associated Symbioniaceae and bacterial community compositions.