Central nervous system involvement in multiple myeloma (CNS-MM) is a rare condition. Various manifestations of CNS-MM have been reported, including dural, parenchymal, and leptomeningeal involvement. Among them, leptomeningeal involvement is less common and intraventricular involvement is exceptional, with only one case reported in the literature. Herein, we report the first case of CNS-MM manifesting as an intraventricular mass with leptomeningeal involvement combined with perineural spread. We also describe characteristic computed tomography and magnetic resonance imaging findings of intraventricular multiple myeloma.