Mullerianosis is a rare, complex, benign tumor most commonly found in the bladder and often mistaken for a neoplastic lesion. Herein, we report a case of mullerianosis in a 65-year-old woman who presented with an incidental 2 cm bladder mass found on cross-sectional imaging. A mixed cystic and solid tumor was identified on cystoscopy and a transurethral resection of the suspected tumor was performed with histopathology confirming a final diagnosis of mullerianosis. While an unusual diagnosis, mullerianosis of the urinary bladder needs to be correctly identified to provide appropriate treatment and avoid misdiagnosis.