Peripheral nerve injury is one of the rare complications of adult-onset Still's disease (AOSD). We report a 20-year-old woman diagnosed with AOSD combined with severe sensory neuropathy. She presented with a sore throat, joint pain, rash, and lymphadenopathy. After receiving glucocorticoid therapy, her fever, rash, and inflammatory markers improved. Unexpectedly, 3 weeks after the onset, she experienced sudden paresthesia in her extremities, decreased muscle strength, and diminished tendon reflexes. The electrophysiological examination and peripheral nerve biopsy confirmed immune-mediated severe sensory neuropathy. For the first time, we report typical Wallerian degeneration in AOSD patients with sensory neuropathy by nerve biopsy. Compared with other common symptoms, the delayed aggravation of neurological symptoms may be an important characteristic of sensory neuropathy secondary to AOSD. We emphasize that intensive attention to neurological symptoms after general symptoms control, administration of adequate and appropriate prolonged immunosuppressive therapy, and long-term follow-up are essential for these patients.