Hymenochaetales Oberw. comprises a group of fungi that commonly shares characteristics such as causing white rot, bearing setae, and having an imperforate parenthosome and no clamps. However, they exhibit various macromorphological characteristics, including clavarioid, effused, resupinate, stipitate stereoid, and stipitate lamellate basidiomes. Most species are classified under two well-known families, Hymenochaetaceae Imazeki & Toki and Schizoporaceae Jülich, from thirteen known families in Hymenochaetales. The remaining eleven families are relatively new, mostly monogeneric, with a limited number of species and little research conducted. A multifaceted morphological and multigenetic marker-based phylogenetic investigation was conducted to comprehensively understand the true diversity of Hymenochaetales in the Republic of Korea. Five genetic markers were assessed for the phylogenetic analysis: nuclear small subunit ribosomal DNA (nSSU), internal transcribed spacer (ITS), nuclear large subunit ribosomal DNA (nLSU), RNA polymerase II subunit 2 (RPB2), and translation elongation factor 1 (TEF1). Our findings revealed one new species, Rickenella umbelliformis sp. nov., and identified four formerly unreported species classified under four understudied families. Additionally, we updated taxonomic classifications for all indigenous Hymenochaetales species from the understudied families. Our findings contribute to a better understanding of Hymenochaetales diversity and highlight the need for continued research.