Ethnomedicine, a holistic approach integrating plants, spirituality, and the natural world, has long served as a fundamental source of healing. In the Eastern Himalaya region, particularly Arunachal Pradesh, medicinal plants play a pivotal role in cultural, spiritual, and healthcare domains. Despite extensive documentation of traditional medicinal plant use by various tribal communities in North-East India, comprehensive exploration in Arunachal Pradesh remains scarce. This study aims to fill this gap by compiling indigenous knowledge of medicinal plants in the region, focusing on traditional uses, plant parts utilized, medicinal properties, and their richness distribution across elevational gradients. Data compilation from 199 sources facilitated the identification of 508 medicinal plant species spanning 158 families. Leaves, fruits, and roots emerged as primary plant parts utilized in traditional medicine. The study employed a Generalized Additive Model (GAM) to analyze species richness across elevation gradients. The model featuring an automatic smoothing term, emerged as the best-fit model, effectively elucidating the relationship of medicinal plant richness over elevation gradients of the state. The richness map revealed concentrations of medicinal flora in the tropical Himalayan region, emphasizing the ecological significance of conservation efforts. The findings underscore the region's ecological uniqueness and the importance of preserving its rich medicinal plant biodiversity for future generations.