Atypical teratoid/rhabdoid tumors (AT/RT) rarely occur in the cauda equina; thus, the clinical behavior and optimal treatment remain unclear. A 9-year-old boy presented with a rapidly progressing intradural extramedullary tumor at the L2–5 level, underwent tumor resection, and was diagnosed with AT/RT. His gait disturbance improved postoperatively, and he received adjuvant chemotherapy and radiotherapy. In 5 months of follow-up, recurrence was not observed. Although extremely rare, AT/RT should be included in the differential diagnosis, as it requires prompt therapeutic intervention. Safe resection with minimal functional impairment, followed by postoperative chemoradiation, can lead to tumor control and improve neurological function.