Delayed encephalopathy after carbon monoxide (CO) intoxication involves a triad of characteristic symptoms consisting of mental deterioration, urinary incontinence, and gait disturbance. Additionally, while it is not normally associated with involuntary movement, delayed encephalopathy after CO intoxication can also, in extremely rare cases, lead to chorea. We report a patient with delayed encephalopathy due to CO intoxication, suffering from chorea involving a unilateral lower limb, and subsequent cognitive impairment and other extrapyramidal symptoms.