Peritoneal surface malignancies (PSMs) represent a complex spectrum of tumors that can originate primarily from the peritoneum or, more commonly, develop due to metastases from gastrointestinal or genitourinary sites. Risk factors for peritoneal metastases are attributable to the primary site of origin and often include high T stage, tumor perforation, high tumor grade, other metastases, and incomplete prior resection. Assessment of the peritoneal disease burden through cross-sectional imaging and laparoscopy/laparotomy is essential for planning treatment. Staging of PSM is done using scoring systems such as the peritoneal carcinomatosis index (PCI) score. Multidisciplinary management is essential and is tailored based on disease grade, PCI, and patient factors. Curative-intent treatment in well-selected patients includes cytoreductive surgery with or without hyperthermic intraperitoneal chemotherapy (HIPEC) and systemic chemotherapy. Palliative treatment can involve a combination of palliative surgery, debulking, systemic therapies, and supportive care.