Background: Retrospective studies using spontaneous reporting system databases have provided a great understanding of adverse drug reactions (ADRs) in the real world, complementing the data obtained from randomized controlled trials. However, there have been few reports on large-scale epidemiological studies on the adverse effects of antipsychotics in Asia. Aim: This study aimed to investigate the characteristics of antipsychotic ADRs using a nationwide pharmacovigilance database. Methods: Data were collected from the Korea Adverse Event Reporting System database between 2010 and 2019. The study subjects were selected using the International Classification of Disease codes for diseases related to psychosis and Electronic Data Interchange codes for amisulpride, aripiprazole, clozapine, haloperidol, olanzapine, paliperidone, quetiapine, risperidone, and ziprasidone. The causality assessment of “possible,” “probable,” or “certain” by the World Health Organization–Uppsala Monitoring Center System causality category was selected. All data were descriptively analyzed. Results: In total, 5067 adverse events associated with antipsychotic drugs were reported. The antipsychotics that commonly resulted in ADRs were quetiapine (47.7%), olanzapine (11.3%), and clozapine (10.7%). Serious ADRs were most commonly observed with clozapine. Gastrointestinal and central nervous system problems occurred within a month when ADRs were classified according to the time of onset. In contrast, metabolic and bone marrow-related symptoms occurred after long-term use. Sedation and nausea were the most common ADRs in children and adolescents, whereas constipation and dizziness were common in adults and the elderly. Conclusions: This study extends our knowledge of antipsychotic ADRs in the Asian population.