Brazil is known as a center of diversity for several plant families. Among these, Acanthaceae are especially diverse in the Cerrado, which is home to ca. 150 species, many of which are endemic. Recent field and herbarium studies of Ruellia of the Cerrado in Goiás and Distrito Federal have led to the discovery of 9 species new to science, which we formally describe as R. altoparadisensis, R. cataractae, R. ceciliae, R. chapadensis, R. glandulifolia, R. hatschbachii, R. lucindae, R. mellosilvae, and R. pinguicula. In addition to botanical illustrations, we provide information about their geographical distributions, habitats, phenologies, and preliminary conservation status. Species are discussed in the context of the Cerrado physiognomies and sub-biomes, which are delimited. We additionally propose one new combination (R. rosmarinus), two lectotypifications (R. pohlii and R. adenostachya), and an identification key to Ruellia species that occur Brazilian Cerrado.