Here we describe Vahiny depereti, gen. et sp. nov., a new titanosaur dinosaur from the Upper Cretaceous Maevarano Formation of northwestern Madagascar. Vahiny is distinguished from other titanosaurs by characteristics of the basal tubera, basipterygoid processes, parasphenoid, and cranial nerve foramina. Diagnostic cranial material of Vahiny formalizes the long-standing hypothesis that two titanosaur genera were present in the Late Cretaceous of Madagascar. The other titanosaur, Rapetosaurus krausei, is the most common dinosaur in the fauna and is known from hundreds of bones, including multiple partial skeletons and skulls. In contrast, non-Rapetosaurus elements are extremely rare. Of these elements, which have been called ‘Malagasy Taxon B,’ we identify a partial braincase as the holotype of Vahiny depereti. Although Vahiny and Rapetosaurus coexisted on the island of Madagascar, differences in their braincases indicate that they are not closely related to one another. Instead, Vahiny is most similar to Jainosaurus from the Late Cretaceous of India, and shares similarities with the South American taxa Muyelensaurus and Pitekunsaurus.