Pavonia secreta (Malvaceae) is a new species from Rio Grande do Sul, Brazil. This new species belongs to subgenus Pavonia and is related to P. xanthogloea. Pavonia secreta can be distinguished by the absence of a tuft of long and simple trichomes at the apex of the petiole and on the abaxial side of the leaf, and by paler foliage; it presents dark pink flowers, with larger petals and stem tube; has larger mericarps, which are tuberculate-rugose with 2–3 tubercules on each side. Pavonia secreta is an endemic species restricted to Pedra do Segredo, Morro do Leão and a neighbouring hill, localities that belong to Caçapava do Sul municipality, in southern Brazil. We present a morphological description, illustrations, and ecological data, as well as a key including a morphologically similar species.