Machaerium is a predominantly Neotropical genus with around 130 species of trees, shrubs, and lianas occurring from southern Mexico to northern Argentina. In Brazil there are about 80 species, with the highest diversity occurring in the Atlantic and Amazonian forests. Our taxonomic revision of Machaerium in the Atlantic Forest included field studies in the northeast, southeast, and south of Brazil as well as the analysis of collections that belong to 40 herbaria, which has allowed the study of about 10,300 specimens. For the recognition of taxa, the material studied was compared with the original descriptions of the species and its nomenclatural types. As a result we recognize 41 species of Machaerium in the Atlantic Forest, including the three new species described here: M. androvillosum, M. aureum, and M. robsonnianum. We also designate two neotypes, 20 lectotypes, seven epitypes, and 23 new synonyms for 20 species of Machaerium. In addition to the descriptions and illustrations of the new species and nomenclatural updates, a revised key for all species of the Atlantic Forest with their geographical distributions is presented.