The patient is an 80-year-old woman who initially underwent transurethral resection of a bladder tumor (TURBT) 7 years ago for bladder cancer at another hospital and was diagnosed with urothelial carcinoma (UC), high grade, pT1, followed by 8 cycles of intravesical BCG instillation therapy. Subsequently, her voiding urine cytology began to show suspicion of malignancy. When voiding urine cytology started to show positive findings, two transurethral biopsies of bladder mucosae and one selective upper tract urine cytology were performed with no evidence of malignancy, so she was followed up as an outpatient. She began experiencing spontaneous pain near the urethra and pain on urination 5 years after the initial TURBT. At this time, cystoscopy revealed redness on the posterior bladder wall. Additionally, redness of the vagina and induration of the labia were observed, raising suspicion of Paget's disease or Bowen's disease. She underwent a biopsy of the vulvar, which revealed UC. Ultimately, biopsies of the bladder, urethra, and vulvovaginal regions were performed at our hospital to determine a treatment plan. Immunohistochemical staining of the vulva was positive for cytokeratins 7 and 20 and negative for GCDFP15, confirming a diagnosis of extramammary Paget disease secondary to bladder CIS. As a result, the patient underwent radical surgery, including removal of the vagina, uterus, bladder, and labia. Pathological findings showed extensive CIS in the vagina and labia majora. Herein, we report a very rare case of secondary extramammary Paget disease extending from bladder CIS to the vagina and labia.