Cushing's disease (CD), also known as adrenocorticotropic hormone (ACTH)-dependent pituitary Cushing's syndrome, is a rare and serious chronic endocrine disease that is usually caused by a pituitary adenoma (especially a pituitary microadenoma). Meningioma is the most common type of primary intracranial tumor and is usually benign. The patient in this case report presented with CD coexisting with pituitary microadenoma and meningioma, which is an extremely rare comorbidity. The pathogenesis of CD associated with meningioma remains unclear. Here, we describe the case of bilateral lower extremity edema, lower limb pain, abdominal purplish striae, and abdominal distension for 9 months in a 47-year-old woman. Two years ago, the patient underwent a hysterectomy at a local hospital for hysteromyoma. She had no previous radiotherapeutic treatment or other medical history. Magnetic resonance imaging of her head revealed a sellar lesion (7.8 mm × 6.4 mm) and a spherical mass (3.0 cm × 3.0 cm) in the right frontal convexity. Her level of serum adrenocorticotropic hormone (ACTH) was 169 pg/mL, and her cortisol levels were 933 nmol/mL and 778 nmol/mL at 8 am and 4 pm, respectively. Preoperatively, she was diagnosed with ACTH-secreting pituitary microadenoma and meningioma. Excision of the meningioma was performed through a craniotomy, while an endoscopic endonasal transsphenoidal approach was used to remove the pituitary adenoma. Meningioma and pituitary adenoma were confirmed by postoperative pathology. On the basis of this unusual case, the relevant literature was reviewed to illustrate the diagnosis and treatment of Cushing's disease and to explore the pathogenesis of pituitary adenoma associated with meningioma.