Haemaphysalis concinna (Acari: Ixodidae) is a medically important ixodid tick species widely distributed across Eurasian forest-steppe ecosystems. Despite its broad geographic range, its occurrence in eastern Mongolia has not previously been confirmed. The present study documents the first verified record of H. concinna in the Khalkh Numrug basin, Dornod Province, thereby extending the known distribution of the species within the Greater Khingan region. Tick sampling was conducted at six sites within the Numrug Strictly Protected Area between April and August over a three-year period. Sampling habitats included lakeshores, riverbanks, and marsh-associated forest vegetation. A total of 1,014 specimens morphologically consistent with H. concinna were collected. Among these, 148 specimens were selected for molecular analysis. Species identification was confirmed using mitochondrial 16S rRNA and cytochrome c oxidase subunit I (Cox1) gene markers. Sequence analyses demonstrated 99.8–100% identity with reference sequences from Russia and China available in GenBank. These molecular results, combined with diagnostic morphological characteristics of adult specimens, provide robust confirmation of species identity. This finding represents the first verified occurrence of H. concinna in eastern Mongolia and contributes important baseline data for regional tick biodiversity assessments. The presence of this species in the Khalkh Numrug basin highlights the need for further investigation into its seasonal dynamics, host associations, and potential role in the transmission of tick-borne pathogens in Mongolian forest-steppe ecosystems. These findings provide essential baseline data for vector surveillance and tick-borne disease risk assessment in eastern Mongolia.