Purpose: The purpose of this study was to investigate the combined influence of screen based sedentary behavior and sleep duration on obesity, depression, and suicidal ideation in Korean Adolescents. Methods: This cross sectional study used secondary data from the 2013 Adolescent Health Behavior Online Survey. A total of 27,929 high school students were included in the study. Logistic regression was used for analysis of the combined influence of screen based sedentary behavior and sleep duration on obesity, depression, and suicidal ideation. Results: Obesity was more prevalent among adolescents who had ${geq}$ 4h of screen based sedentary behavior and <7h of sleep duration compared to the reference group, defined as < 2h of screen time and > 7h of sleep duration. Depression and suicidal ideation were more prevalent among adolescents who had 2-4h of screen based sedentary behavior and <7h of sleep duration compared to the reference group. Conclusion: Based on the results of this study, maintaining a low (< 2h) level of screen based sedentary behavior and appropriate sleep duration over 7 hours per day is essential for prevention of adolescent obesity, depression, and suicidal ideation.