A 43-year-old man presented with chronic left hip pain that had increased in severity in the last week. Imaging studies discovered a mass in the iliopsoas muscle. The mass was excised, and pathological examination revealed pleomorphic rhabdomyosarcoma. The patient was followed up for 2 years and demonstrated no recurrence, with good clinical results. Clinicians should follow a systematic diagnostic approach involving a detailed medical history, a comprehensive physical examination, imaging studies, and laboratory tests to evaluate masses in the iliopsoas region, leading to timely diagnosis and appropriate management. Rhabdomyosarcoma is already a rare malignancy in adults. Therefore, having it in the iliopsoas compartment makes this case unique. To our knowledge, there was only one previously reported case of rhabdomyosarcoma involving the iliopsoas.