Metastases are the main cause of death among patients with bladder cancer, which is the second most common malignancy of the genitourinary tract and is highly prevalent in the southwestern region of Taiwan. Angiogenesis plays a critical role in tumor growth and metastasis processes and has relevance in disease recurrence, pelvic lymph node metastasis and poor prognosis. Cancer cells can produce several angiogenesis-stimulating factors involved in vascular growth, including vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and inflammatory cytokines such as interleukin (IL)-8. Common chemotherapeutic drugs for intravesical instillations usually cause major side effects, including urinary frequency, urinary urgency, cystitis, and hematuria. In order to identify a less cytotoxic therapeutic agent that can inhibit tumor cell proliferation, we examined the traditional Chinese herbal medicine Cortex Moutan—reported to have antibacterial, antiviral, anti-inflammatory, antithrombotic, and antitumor properties—for its effects on bladder cancer cell proliferation and expression of angiogenic factors. Our results revealed that Cortex Moutan exhibited high selectivity in inhibiting the growth of bladder cancer cells and also reduced the expression of angiogenesis-stimulating factors in those cells. Thus, we suggest that Cortex Moutan might be used as a cancer therapy drug for bladder’s intravesical chemotherapy in the future.