Madagascar, renowned for its unique biodiversity, harbors the Ankaratra Mountain, the third highest peak on the island. Despite its ecological significance, the ethnobotanical aspects of this region remain largely unexplored. This study aims to investigate the diversity of medicinal plant species, identify commonly used species in traditional medicine, and explore their applications in treating diseases. During the ethnobotanical survey, voucher specimens collected from the botanical inventory were presented to 26 traditional healers in the study area, selected based on their recognized expertise and extensive experience in traditional medicine. Data on plant usage, the specific parts harvested, and preparation methods for herbal remedies were gathered through semi-structured interviews. The study identified 203 medicinal plant species in the Ankaratra Mountain, with 139 (73.9%) endemic and 69 (33.9%) newly recorded in the ethnopharmacopeia. Savannah vegetation was the most cited habitat (35.5%), while endemic species dominated, comprising 77.8% of the most used and 71.6% of the most significant plants. These species were primarily used to treat locally prevalent diseases and those requiring specialized knowledge, underscoring their importance in traditional healthcare. This study provides the first comprehensive ethnobotanical report on the plant species of the Ankaratra Mountain. The findings bear implications for local healthcare practices and contribute to the potential conservation of this unique flora. Further avenues of research include investigating the ecological preferences of endemic species and conducting chemical and pharmacological analyses to uncover novel therapeutic compounds.