A new haplostemonous species of Graptopetalum (subg. Glassia, Crassulaceae) from the Sierra de Coalcomán, Michoacán, is described and illustrated. It differs from its morphologically closest species, G. pentandrum, by having a smaller rosette diameter, broadly oblong leaves, its basal inflorescence branch with fewer flowers than in the rest of branches, a smaller flower diameter, wider petals, and its petal color pattern. It was assessed as Critically Endangered (CR) following the IUCN criteria. A key to the haplostemonous species of Graptopetalum (subg. Glassia) is provided.