Croton section Geiseleria encompasses 82 species in the Americas, but its center of origin and diversity is in Brazil, where 53 species are distributed especially in areas of Cerrado, in the central part of the country. Taxonomic knowledge of several taxa of Croton section Geiseleria is still scarce, and they are frequently misidentified in Brazilian herbarium collections due to their very similar morphology. During a taxonomic study of this section in the Midwest region of Brazil, a new species was found in the state of Mato Grosso. Croton rhodotrichus is herein described, illustrated, and its relationships with the most morphologically similar species, C. glandulosus and C. hirtus, are discussed. Additionally, distribution, habitat, flowering, fruiting, and conservation status of the new species, as well as a key to identify all the species of Croton section Geiseleria present in the state of Mato Grosso are provided.