This report presents a rare case of acute transverse myelitis (ATM) after mumps infection in a 33-year-old male. Symptoms included fever, parotid and scrotal swelling, and subsequent sensory-motor paraparesis. Magnetic resonance imaging revealed long-segment spinal cord hyperintensity, and cerebrospinal fluid analysis showed pleocytosis and elevated protein, with positive mumps virus antibodies. Treatment with high-dose pulse steroids resulted in significant improvement. This underscores the association between mumps and ATM in adults, suggesting an autoimmune-inflammatory mechanism. The favorable response to steroid therapy emphasizes its efficacy in managing mumps-associated ATM. Recognizing such neurological complications is crucial for prompt diagnosis and appropriate intervention.