Myrcia vinacea is a new species endemic to the Coastal Atlantic Forest of São Paulo. It is morphologically similar to M. tetraphylla in vegetative features once both share verticillate leaves. However, it differs by its flaking or smooth trunk bark (vs. rough, non-flaking bark), inflorescences with secondary axes, 10–23 cm long (vs. usually without secondary axes, when present, ca. 2 cm long), pedicellate flowers, (vs. sessile), caducous bracts (vs. persistent), and inflorescences and ovaries with reddish trichomes (vs. brownish to grayish). A comparison with other similar species, diagnosis, description, ecological comments, photographic plates, and distribution map are also provided. Myrcia vinacea is preliminarily classified as Vulnerable (VU) due to the decrease in habitat quality and its restricted area of occupation, with few mature individuals.