Mesenchymal tumors of the genitourinary tract account for 5% percent of bladder malignancies and there are currently 35 documented cases of osteosarcoma type. Concomitant involvement of the prostate in mesenchymal genitourinary malignancies is even rarer. Herein we describe a case of a 72-year-old male with a history of radiation for prostate cancer who develops hematuria. A hematuria evaluation revealed osteosarcoma of the bladder and prostate. He underwent radical cystoprostatectomy with ileal conduit and adjuvant chemotherapy. His disease progressed despite treatment and he elected palliative care 10 months after initial resection. This case reviews a rare histological variant of genitourinary malignancy.