Mesotheliomas are a rare malignancy of the serosal membrane. Mainly it affects the pleural surfaces followed by the second most common location, "peritoneum." The disease follows an aggressive pattern of spread, and by the time the diagnosis is established, the condition significantly spreads to distant locations. Diagnosis of malignant peritoneal mesothelioma is typically made by tissue biopsy. The standard treatment is radical resection; however, patients have benefited from several other modalities. The current case report describes a unique case of malignant mesothelioma, biphasic peritoneal mesothelioma (BPM), which comprises less than 25% of all peritoneal mesotheliomas. The diagnosis and treatment do not differ from other subtypes; however, the prognosis is poor, and if untreated, the survival is typically less than six months.