Tumor-to-tumor metastasis of breast carcinoma to meningioma is a rare phenomenon. It is likely underdiagnosed given the relatively high prevalence and comorbidity of these two primary tumor types, the lack of standardized methodologies for its diagnosis, and the tendency to obfuscate this lesion with simple meningioma or cerebral metastasis of breast carcinoma. Careful histopathologic study of the resected meningioma is the cornerstone of diagnosis of these lesions, although certain conventional radiological features along with specialized modalities may clue the diagnosis. Vigilance for this lesion is appropriate in selected patients with known breast cancer or meningioma, as the two are often coexistent in the same patient, permitting tumor-to-tumor metastasis. Detection of this rare disease process may alter the treatment plan and prognosis. Here, we report a case of breast carcinoma-to-meningioma metastasis in a patient who developed subacute neurological decline while undergoing long-term treatment of her primary, late-stage breast cancer.