Objective Many depressed adolescents do not seek professional help despite there being evidence-based treatments for depression, such as cognitive behavioral therapy or computer-based therapy. To increase professional help-seeking behavior in depressed adolescents, it is necessary to positively change help-seeking attitudes. This study aimed to explore the effect of sub-groups of help-seeking attitudes, gender, and depression level on adolescents’ help-seeking intentions and their perceptions of computer-based psychotherapy. Methods Participants were 246 adolescents aged 13–18 years recruited from six middle and high schools in South Korea. Measures were self-administered questionnaires, and included the Patient Health Questionnaire-9, the Attitudes Toward Seeking Professional Psychological Help Scale, the Intention to Seek Counseling Inventory, Preferences for Depression Treatment, and the Perceptions of Computerized Therapy Questionnaire. Results Help-seeking intentions were positively related with female gender and the recognition of the need for help. A higher level of confidence in therapists was related to high preference for computer-based therapy and face-to-face therapy. Adolescents with more severe depression were more likely to prefer pharmacotherapy. The perceptions of computer-based therapy were more positive in male adolescents, and in adolescents with a higher level of confidence in therapists yet a lower level of interpersonal openness. Conclusion To promote adolescents’ help-seeking behavior, improvement of the recognition of the need for help is required, especially among male adolescents. Computer-based therapy provides an alternative for male adolescents with high confidence in therapists yet low interpersonal openness. Consideration of the help-seeking attitudes and gender is needed when providing therapeutic intervention to depressed adolescents