Objective <p>To summarize the clinical manifestations, electroencephalographic and imaging characteristics of pediatric-onset Huntington’s disease (PoHD), and to evaluate the therapeutic potential of aripiprazole for PoHD.</p> Methods <p>We conducted a retrospective analysis of clinical and genetic data from a PoHD patient diagnosed and treated at the Department of Pediatrics, First Affiliated Hospital of Harbin Medical University, with a systematic evaluation of the therapeutic efficacy through of aripiprazole longitudinal follow-up.</p> Results <p>The patient presented with pre-school-onset manifestations characterized by choreiform movements and gait instability, progressing to near-complete motor loss within 6 months, accompanied by sleep initiation difficulties from persistent chorea. Cranial magnetic resonance imaging (MRI) revealed cerebellar tonsillar atrophy while interictal electroencephalogram (EEG) demonstrated epileptiform discharges localized to the left occipitotemporal region, characterized by spikes, spike-and-slow-wave complexes, and sharp-and-slow-wave complexes. Molecular analysis confirmed an expanded CAG repeat (99 repeats) in the pathogenic allele. Significant amelioration of sleep architecture was observed within two weeks of aripiprazole initiation, followed by progressive improvements in voluntary motor control and a marked decrease in choreiform movements at the 4-month follow-up assessment.</p> Interpretation <p>PoHD is epidemiologically rare and has nonspecific clinical manifestations. Early implementation of CAG repeat expansion analysis enables precise diagnosis. Aripiprazole alleviates motor and psychiatric symptoms and has favourable tolerability in patients with PoHD.</p>