Objective: This study aimed to identify temperament and character profiles associated with internalizing and externalizing problems in children with attention deficit hyperactivity disorder (ADHD). Methods: Children with ADHD (n=114, 8.51±1.87 years) were selected from the Department of Child and Adolescent Psychiatry at Jeju National University Hospital. They were diagnosed by Kiddie-Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version and evaluated using the Advanced Test of Attention and Korean Wechsler Intelligence Scale for Children-Fourth Edition. Their parents completed the ADHD Rating Scale, Korean-Child Behavioral Checklist, and Junior Temperament and Character Inventory. Results: The participants with both internalizing and externalizing problem had more severe ADHD symptoms and significantly higher novelty seeking, harm avoidance, and self-transcendence, as well as lower self-directedness and cooperativeness than those who had not comorbid problems. Harm avoidance was correlated with their level of internalizing problems regardless of severity of ADHD symptoms. In addition, novelty seeking and sex (male) were being associated with the level of externalizing problems. Conclusion: Differences were observed in the temperament and character profiles of children with ADHD according to their comorbid psychopathology. Results suggested that temperament and character profiles may affect the comorbid psychopathology in children with ADHD regardless of ADHD symptom severity.