TheAmanitasubgenusAmanitinacontains six sections, and the species diversity of this subgenus has still not been explored in Thailand. Twenty samples collected in 2019 and 2020, which had the morphological characteristics of theAmanitasubgen.Amanitina, were observed in this study. Both the microscopical characteristics and multi-gene phylogenetic analyses of the ITS, nrLSU,RPB2,TEF1-α, andTUBgene regions revealed that the 20 samples represented nine species and dispersed into four sections. Remarkably, three taxa were different from any other currently known species. Here, we describe them as new to science, namelyA. albifragilis,A. claristriata, andA. fulvisquamea. Moreover, we also recognized six interesting taxa, including four records that were new to Thailand, viz.A. cacaina,A. citrinoannulata,A. griseofarinosa, andA. neoovoidea, as well as two previously recorded species,A. caojizongandA. oberwinkleriana. Moreover, we provide the firstRPB2andTEF1-αgene sequences forA. cacaina. Detailed descriptions, illustrations as line drawings, and comparisons with related taxa are provided.