Bladder endometriosis causes urinary symptoms including frequency, dysuria, cyclic haematuria and non-urinary pain symptoms. To our knowledge, the association of bladder endometriosis with urinary incontinence has not been described. We present the first case of bladder endometriosis that caused urinary symptoms including mixed urinary incontinence (MUI). A 34-year-old nulliparous woman was referred to our urogynaecology clinic with a 18-month history of urgency urinary incontinence (UUI) and stress urinary incontinence (SUI). A diagnosis of bladder endometriosis was performed on the basis of symptoms and imaging. The patient refused surgery and dienogest was prescribed. At the 12-month follow-up, all endometriosis-related symptoms and questionnaire scores had significantly improved, and there was resolution of the abnormal urodynamic findings. In reproductive-aged women suffering pain symptoms, bladder endometriosis should be considered in the differential diagnosis of urinary incontinence and treatment with dienogest may lead to improvement of both urinary and pain symptoms.