Tumor lysis syndrome (TLS) is a life-threatening oncological emergency that frequently occurs in patients with hematological malignancies. It is becoming more common in patients with solid tumors because of advances in molecular targeted therapies. Recombinant urate oxidase (rUO) is effective at preventing and treating hyperuricemia, but clinicians who treat adult patients with solid tumors are generally not aware of this. In addition, the treatment guidelines for TLS do not include indications for rUO treatment for chemosensitive sarcoma. We report an adolescent case of metastatic rhabdomyosarcoma (RMS), in which clinical TLS was successfully prevented using rUO. A 16-year-old Japanese male suffered from urinary retention and bone pain and was diagnosed with prostate RMS combined with multiple bone metastases and bone marrow involvement. He was judged to be at high risk of clinical TLS because his prostate tumor was bulky and he displayed laboratory TLS. rUO was administered during chemotherapy. Soon after the initiation of chemotherapy, his disseminated intravascular coagulation (DIC) got worse, and his lactate dehydrogenase (LDH) level was elevated due to tumor lysis. However, his serum uric acid levels remained low, and he was prevented from falling into acute renal failure. The planned regimen was successfully completed without life-threatening complications, and the patient achieved a complete response after 2 courses of chemotherapy. The international TLS consensus panel developed recommendations for TLS prophylaxis, but did not define the TLS risk classification of RMS. We recommend that RMS should be treated like neuroblastoma because it grows rapidly and is highly chemosensitive. Our patient was considered to be indicated for rUO because he displayed urinary retention, DIC, and laboratory TLS before chemotherapy. These features might be useful as indications for rUO therapy, which can safely support chemotherapy.