Plasmacytoma is a rare neoplastic disorder that arises from B-lymphocytes. Solitary bladder plasmacytoma, a type of solitary extramedullary plasmacytoma, is even rarer. Treatments for solitary extramedullary plasmacytoma include surgery, chemotherapy, and radiation. However, there are no clinical trials or guidelines specifying which treatment might represent the gold standard.We herein report a case of a 51-year-old woman with solitary bladder plasmacytoma (SBP). There remains no consensus regarding the optimal treatment for SBP. However, we successfully treated her with transurethral resection of bladder tumor followed by postoperative radiotherapy (50 Gy/25 F). The patient remained free of tumor recurrence at a 7-mo follow-up.Radiation is the potential main treatment for SBP. However, surgery is also necessary.©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.