Actinomycosis is a rare chronic bacterial infection primarily caused by Actinomyces israelii. A 47-year-old woman presented to our clinic with a 1-week history of lower abdominal pain. Preoperative imaging studies revealed multiple peritoneal and pelvic masses suggestive of malignancy. The primary tumor could not be identified despite further endoscopic and gynecological evaluation. On exploration for tissue confirmation, excisional biopsies from multiple masses were performed because complete excision was not possible. Histopathological examination confirmed actinomycosis with multiple abscesses, and the patient was treated with antibiotics. We present a case of disseminated peritoneal actinomycosis that mimicked malignant peritoneal carcinomatosis on imaging studies.