Thismia limkokthayi, a distinct mitriform species of the mycoheterotrophic genus Thismia, is described and illustrated. It was found at a locality in the upland areas of Genting Highlands, Pahang, Malaysia. This new species is morphologically similar to members of Thismia sect. Geomitra, but differs in several characteristics, including the colour of the floral tube, the inner surface of the floral tube with longitudinal ribs and absent transverse bars, a stamen apex with a central lobe (prolongation of the rib) and two lateral lobes (the tips of each are recurved) and a black-purplish stigma. Thismia limkokthayi is provisionally classified as Critically Endangered according to the IUCN Red List Categories and Criteria.